At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a new
facility (TRImP) is under development. It aims for producing, slowing down, and
trapping of radioactive isotopes in order to perform accurate measurements on
fundamental symmetries and interactions. A production target station and a dual
magnetic separator installed and commissioned. We will slow down the isotopes
of interest using an ion catcher and in a further stage a radiofrequency
quadropole gas cooler (RFQ). The isotopes will finally be trapped in an atomic
trap for precision studies.Comment: Proceedings of the XXIX Mazurian Lakes Conference on Physics (Sep.
  2005, Piaski, Poland

Sohani, M.

English

arXiv

Sohani, M

University of Groningen

   University of GroningenTRI mu P - A new facility to produce and trap radioactive isotopesSohani, M; TRImuP GrpPublished in:Acta Physica Polonica BIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2006Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Sohani, M., & TRImuP Grp (2006). TRI mu P - A new facility to produce and trap radioactive isotopes. ActaPhysica Polonica B, 37(1), 231-238.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 12-11-2019Vol. 37 (2006) ACTA PHYSICA POLONICA B No 1TRIµP — A NEW FACILITYTO PRODUCE AND TRAP RADIOACTIVE ISOTOPES∗M. Sohanifor the TRIµP group [1]Kernfysisch Vensneller InstituutZernikelaan 25, 9747 AA Groningen, The Netherlands(Received November 23, 2005)At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a newfacility (TRIµP) is under development. It aims for producing, slowingdown, and trapping of radioactive isotopes in order to perform accuratemeasurements on fundamental symmetries and interactions. A productiontarget station and a dual magnetic separator installed and commissioned.We will slow down the isotopes of interest using an ion catcher and ina further stage a radiofrequency quadropole gas cooler (RFQ). The isotopeswill finally be trapped in an atomic trap for precision studies.PACS numbers: 25.70.–z, 25.70.Mn, 29.70.–h, 32.80.Pj1. IntroductionRare and short lived radioactive isotopes are of interest because theycan offer unique possibilities for investigating fundamental physical symme-tries [2]. Fundamental symmetries are at the basis of the Standard Model(SM). Using radioactive isotopes, limits for the validity of the SM can beexplored in high precision measurements. In particular, high accuracy canbe achieved, when suitable radioactive isotopes are stored in atom or iontraps [3, 4].The TRIµP (Trapped Radioactive Isotopes: µicrolaboratories for fun-damental Physics) facility at the Kernfysisch Vensneller Instituut (KVI) inGroningen, The Netherlands, is being developed to conduct such high pre-cision studies. The local group concentrates on precision measurements ofnuclear β decays [5] and search for permanent electric dipole moments [5].We will briefly describe the complete facility consisting of a production tar-get, a Magnetic Separator with cooling stages and atom traps. We willdescribe also the method of the precision measurements in β decay studies.∗ Presented at the XXIX Mazurian Lakes Conference on PhysicsAugust 30–September 6, 2005, Piaski, Poland.(231)232 M. Sohani2. Magnetic separatorHeavy-ion beams from the superconducting cyclotron AGOR at KVIare used to produce a wide range of products (Fig. 1). A hydrogen gastarget cooled to liquid nitrogen temperature [6] and various solid targetshave been employed in different types of reactions, from fusion evaporationto charge exchange. Using inverse kinematics, products are selected by thedual magnetic separator [7].Fig. 1. Layout of the TRIµP separator.The TRIµP separator has been commissioned. The experiments included21Na production using 21Ne (43MeV/n and 20MeV/n). Typical rates were3×103/s/pnA for 21Na. Recently 104 /s/pnA for 19Ne and 103/s/pnA 20Nawas achieved. In a first physics experiment 21Na and 22Mg were used tomeasure branching ratio of 21Na β decay to the excited state and of 21Neat 350 keV [8]. The population of this state is of relevance for β–ν cor-relation measurements [9]. A stack of two silicon detectors registered theincoming particles and the subsequent β decay. A set of Ge detectors de-tected the γ ray emission following part of the β decays. The Ge Cloverdetectors include a BGO Compton-shield to reduce background. The sys-tematic variation in the branching ratio, that has been observed in variousexperiments [10], may have been caused by a line in the ambient backgroundfrom the 238U decay chain (352 keV, 214Pb). This line is clearly seen in thespectrum (see Fig. 2 right-hand side).TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 233Fig. 2. Left-hand side: 21Na β decay scheme. The experiment aims to determinethe fraction f ending in the 5/2+ state. Right-hand side: Observed γ-ray spectra:(a) total spectrum in coincident with β decay; (b) Compton suppressed spectrumof (a); (c) Compton suppressed background spectrum.3. Cooling stagesIn order to perform precision measurements, radioactive ions producedand separated from the primary beam and unwanted products need to becooled and trapped in atom traps. The cooling procedure needs to be fastand efficient in view of the short lifetime of isotopes. For light isotopessuch as 21Na, the high energy and fully stripped secondary beam passesthrough several cooling stages before it can be delivered as a low energyand singly charged ion beam with acceptable emittance. Neutralization andlaser trapping is the last step to collect radioactive atoms in a well definedcold atomic cloud.3.1. Ion CatcherThe main principle of an Ion Catcher is to stop high-energy ions inmatter, i.e. in a gas or a solid. Electronic stopping causes fast slowing. Inorder to extract a low energy ion beam at the end of the ion catching process,the particles must remain ionized. Neutralization of atoms is a poisoningprocess which must be avoided. The commonly used techniques includegas-filled ion catchers and thermal ionizing devices.Gas-filled ion catcher: Collisions and charge exchange processes bringions to lower energies and charge states as long as they move trough thegas. At low energies, re-ionization and neutralization are in competition.234 M. SohaniCross sections of these processes are highly dependent on the energy of theions and the relative ionization potential of the particle and the stoping gas.There are two strategies: one either relies on the survival of the particlesas singly charged ions or on active re-ionization after neutralization. In thelatter case extraction can be done e.g. after resonant laser ionization [12].Principally, the gas-filled ion catcher can only work when the space chargebuilt up during stopping does not hinder the extraction optics. Therefore,the efficiency for this device depends on the input ion rate [12, 13].Thermal ionizer: A device consists of one or several metal foils thatstop the beam. Atoms will diffuse out of the foils particularly at high tem-perature. Collisions with the surface of the foils and the cavity body canionize these atoms. A potential electric field allows to extract ions. Choosingproper material such as W for the stopping foils and the cavity is important.The difference between the ionization potential of the beam element and thefoil element determines the ionization probability and re-neutralization aftereach collision with the surface. Therefore, a thermal ionizer mainly worksfor alkali and alkali-earth elements that have low ionization potential [14].Investigations for both types of devices were performed in the frameworkof the TRIµP program. Because of the priority of the experiments on Naand Ra isotopes, a thermal ionizer is under the construction and will betested soon. A stack of W foils at high temperature has been chosen asstopper inside a hot W cavity.3.2. RFQ cooler and buncherA segmented radio frequency quadrupole cooler and buncher is the sec-ond stage of the cooling procedure in the TRIµP facility. Input ions comingfrom the thermal ionizer have an energy spread of order several eV. In thefirst part of the RFQ, they pass through a low-pressure gas-filled medium.A longitudinal drag voltage guides them to the exit while confined at thesame time in the transverse direction by a set of radio frequency electricquadrupoles [11]. The second part of the RFQ collects ions in a Paul-trap.By switching the last electrode of the trap, a bunch of ions can be releasedand sent to the atom traps through an electrostatic low-energy beam line.The TRIµP RFQ has been constructed and is commissioned. Measuringthe transmission of the ions and optimizing the settings are the main issuesof the commissioning.3.3. Atomic trapThe β decay experiments at the TRIµP facility will be carried out usinga set of two subsequent magneto-optical traps. The first trap is to collectatoms and bunch them toward the second trap inside a detection chamber.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 235The first trap is made of a small glass cavity and has wide laser beams forefficient collection of atoms. It will contain a hot Yttrium foil to neutralizethe incoming ion beam. The second trap is located in a precision measure-ment chamber that is serving as a reaction microscope, composed of therecoil ion and beta-electron counters.4. β decay spectroscopyCorrelations between particles from β decay manifest the symmetriesand symmetry violations of the weak interaction [15, 16]. In weak interac-tions (a current–current interaction) several currents can contribute. Theseare Scalar (S), Vector (V), Axial-vector (A) and Tensor (T) currents. Inthe Standard Model (SM), the weak interaction is exclusively the result ofV and A currents. The V current is observed in Fermi (F) decay and theA current in Gamow–Teller (GT) decay. Contribution of other currents inβ decay will affect the correlations between the particles and their kinemat-ics. Deviations from the standard V–A model indicates physics beyond theSM.It is not practical to measure the ν particle in β–ν correlations. There-fore, one measures the correlation between the β-electron and recoil ionin order to measure the complete phase-space of the β decay. Recoil-Ion-Momentum Spectroscopy (RIMS) is an advanced method to measure therecoil ion. This method is used at KVI to study charge exchange processwith the recoil energy of the order of eV [17,18]. In RIMS the recoil ions areprojected with an electric field on a position sensitive microchannel platedetector (MCP) (Fig. 3). This method has been used successfully by othergroups for β decay studies [9, 19]. The time of flight measurement of therecoil ion is started by observing a hit in the β-detector and is stopped bythe hit on the MCP. Together with the position of the recoil ion on the MCP,this provides information about the initial momentum. A position sensitiveβ-detector allows to restrict the momentum of the β-electron.Fig. 3. Recoil-Ion-Momentum Spectroscopy sketch.236 M. SohaniThe differential rate of β decay is proportional to the 3-body phase-space and the week interaction matrix element. The general derivation ofthe matrix element (Eq. (1)) shows all the possible correlations between theparticles [20].d2WdΩedΩν ∼ 1 + ap · qˆE+ b ΓmeE+ 〈J〉 ·[ApE+B qˆ +Dp× qˆE]+ 〈σ〉 ·[GpE+Q 〈J〉 +R 〈J〉 ×pE], (1)where p and q are momentum of the β-electron and the neutrino, 〈J〉 and〈σ〉 are polarization of the parent nuclei and the β-electron and E is theenergy of the β-electron. a, b,A,B,D,G,Q and R coefficients depend onthe fundamental weak coupling constants and nuclear matrix elements. TheD and R coefficients are zero if time reversal symmetry is conserved. Ex-perimental searching for finite value of the D and R coefficients requires asample of polarized nuclei (〈J〉 6= 0). For the R coefficient also measuring thepolarization of the electrons is required. We aim primarily at measuring D.In the initial studies without polarization, measuring a and b coefficient ex-plores the effect of the non-SM weak currents. In general, there are two freeparameters out of 9 parameters for the 3-body phase-space, including allthe conservation laws and geometrical symmetries for non-polarized atoms.Therefore, one can choose any pair of the parameters to explore the β decay(a) (b)Fig. 4. An event distribution according to a MC simulation of energy of the recoilion versus energy of the β-particle. (a) distribution for 21Na β decay. (b) differencein the distribution for a 1% smaller value of a as compared to the SM prediction.The sensitivity to a is largest for β energies around 1MeV and recoil ion energiesaround 0.2MeV.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 237events with a 2D histogram. One choice uses the energy of the recoil ionand the β-particle as free parameters to express all the other parametersin terms of these two. A deviation of a from the SM prediction results ina change in the corresponding distribution as showed in Fig. 4.5. Outlook and conclusionThe TRIµP facility is a user facility to deliver radioactive beams and toperform precision measurements. The TRIµP production target and the sep-arator are functioning. A first user experiment has been already completed.Several experiments using a clean radioactive beam have been requested.This work was supported by the Dutch Stichting vor Fundamenteel On-derzoek der Materie (FOM) under programme 48 (TRIµP) and the EU RTDnetwork NIPNET, HPRI-2001-50034.REFERENCES[1] The TRIµP group contributing to this work: G.P. Berg, S. De, S. Dean,O.C. Dermois, U. Dammalapati, P. Dendooven, K. Jungmann, C.J.G. On-derwater, A. Rogachevskiy, M. Sohani, E. Traykov, A. Mol, L. Willmann,H.W. Wilschut.[2] NuPECC Report available from http://www.nupecc.org/pub/.[3] K. Jungmann, Nucl. Phys. A751, 87c (2005).[4] H.W. Wilschut, Hyperfine Interactions 146/147, 77 (2003).[5] K. Jungmann, in Spin 2004, Eds. K. Aulenbacher, T. Bradamante, A. Bressan,A. Matini, World Scientific, Singapure 2005, p. 108.[6] A.R. Young, M. Boswell, G.P. Berg, A. Rogachevskiy, M. Sohani, E. Traykov,KVI Annual Report 2004, p. 17.[7] G.P.A. Berg, O.C. Dermois, U. Dammalapati, P. Dendooven, M.N. Harakeh,K. Jungmann, C.J.G. Onderwater, A. Rogachevskiy, M. Sohani, E. Traykov,L.Willmann, H.W. Wilschut, submited to Nucl. Instrum. Methodsnucl-ex/0509013.[8] L. Achouri, J.-C. Angélique, G. Ban, G.P.A. Berg, B. Blank, G. Canchel,P.G. Dendooven, J. Giovinazzo, K. Jungman, E. Liénard, I. Matea, O. Navilat-Cuncic, N. Orr, A. Rogachevskiy, M. Sohani, E. Traykov, H.W. Wilschut, KVIExperiment P01 and Annual Report 2004, p. 11.[9] N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, P.A. Vetter, Phys. Rev. Lett. 93,102501 (2004).[10] See e.g. D.E. Alburger, Phys. Rev. C9, 991 (1974); H.S. Wilson et al., Phys.Rev. C22, 1696 (1980).238 M. Sohani[11] See e.g. M.D. Lunney, R.B. Moore, International Journal of Mass Spectrom-etry 190/191, 153 (1999).[12] M. Huyse et al., Nucl. Instrum. Methods B187, 535 (2002).[13] D.J. Morrissey, private communication.[14] R. Kirchner, Nucl. Instum. Methods A292, 203 (1990).[15] H.W. Wilschut, AIP Conferance Proceedings 802, 223 (2005).[16] N. Severijns, M. Beck, O. Naviliat-Cunicic, submited to Rev. Mod. Phys.[17] J.W. Turkstra, R. Hoekstra, S. Knoop, D. Meyer, R. Morgenstern, R.E. Olson,Phys. Rev. Lett. 87, 123202 (2001).[18] S. Knoop, M. Keim, H.J. Lüdde, T. Kirchner, R. Morgenstern, R. Hoekstra,J. Phys. B: At. Mol. Opt. Phys. 38, 3163 (2005).[19] A. Gorelov et al., Phys. Rev. Lett. 94, 132501 (2005).[20] J.D. Jackson, S.B. Treiman, H.W. Wyld, Phys. Lett. 106, 517 (1957).

TRI mu P - A new facility to produce and trap radioactive isotopes

At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a new facility (TRI mu P) is under development. It aims for producing, slowing down, and trapping of radioactive isotopes in order to perform accurate measurements on fundamental symmetries and interactions. A production target station and a dual magnetic separator installed and commissioned. We will slow down the isotopes of interest using an ion catcher and in a further stage a radiofrequency quadropole gas cooler (RFQ). The isotopes will finally be trapped in an atomic trap for precision studies

NARCIS 

At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a new facility (TRI mu P) is under development. It aims for producing, slowing down, and trapping of radioactive isotopes in order to perform accurate measurements on fundamental symmetries and interactions. A production target station and a dual magnetic separator installed and commissioned. We will slow down the isotopes of interest using an ion catcher and in a further stage a radiofrequency quadropole gas cooler (RFQ). The isotopes will finally be trapped in an atomic trap for precision studies.</p

ARTS repository - University of Groningen

   University of GroningenTRI mu P - A new facility to produce and trap radioactive isotopesSohani, M; TRImuP GrpPublished in:Acta Physica Polonica BIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2006Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Sohani, M., & TRImuP Grp (2006). TRI mu P - A new facility to produce and trap radioactive isotopes. ActaPhysica Polonica B, 37(1), 231-238.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 17-07-2023Vol. 37 (2006) ACTA PHYSICA POLONICA B No 1TRIµP — A NEW FACILITYTO PRODUCE AND TRAP RADIOACTIVE ISOTOPES∗M. Sohanifor the TRIµP group [1]Kernfysisch Vensneller InstituutZernikelaan 25, 9747 AA Groningen, The Netherlands(Received November 23, 2005)At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a newfacility (TRIµP) is under development. It aims for producing, slowingdown, and trapping of radioactive isotopes in order to perform accuratemeasurements on fundamental symmetries and interactions. A productiontarget station and a dual magnetic separator installed and commissioned.We will slow down the isotopes of interest using an ion catcher and ina further stage a radiofrequency quadropole gas cooler (RFQ). The isotopeswill finally be trapped in an atomic trap for precision studies.PACS numbers: 25.70.–z, 25.70.Mn, 29.70.–h, 32.80.Pj1. IntroductionRare and short lived radioactive isotopes are of interest because theycan offer unique possibilities for investigating fundamental physical symme-tries [2]. Fundamental symmetries are at the basis of the Standard Model(SM). Using radioactive isotopes, limits for the validity of the SM can beexplored in high precision measurements. In particular, high accuracy canbe achieved, when suitable radioactive isotopes are stored in atom or iontraps [3, 4].The TRIµP (Trapped Radioactive Isotopes: µicrolaboratories for fun-damental Physics) facility at the Kernfysisch Vensneller Instituut (KVI) inGroningen, The Netherlands, is being developed to conduct such high pre-cision studies. The local group concentrates on precision measurements ofnuclear β decays [5] and search for permanent electric dipole moments [5].We will briefly describe the complete facility consisting of a production tar-get, a Magnetic Separator with cooling stages and atom traps. We willdescribe also the method of the precision measurements in β decay studies.∗ Presented at the XXIX Mazurian Lakes Conference on PhysicsAugust 30–September 6, 2005, Piaski, Poland.(231)232 M. Sohani2. Magnetic separatorHeavy-ion beams from the superconducting cyclotron AGOR at KVIare used to produce a wide range of products (Fig. 1). A hydrogen gastarget cooled to liquid nitrogen temperature [6] and various solid targetshave been employed in different types of reactions, from fusion evaporationto charge exchange. Using inverse kinematics, products are selected by thedual magnetic separator [7].Fig. 1. Layout of the TRIµP separator.The TRIµP separator has been commissioned. The experiments included21Na production using 21Ne (43MeV/n and 20MeV/n). Typical rates were3×103/s/pnA for 21Na. Recently 104 /s/pnA for 19Ne and 103/s/pnA 20Nawas achieved. In a first physics experiment 21Na and 22Mg were used tomeasure branching ratio of 21Na β decay to the excited state and of 21Neat 350 keV [8]. The population of this state is of relevance for β–ν cor-relation measurements [9]. A stack of two silicon detectors registered theincoming particles and the subsequent β decay. A set of Ge detectors de-tected the γ ray emission following part of the β decays. The Ge Cloverdetectors include a BGO Compton-shield to reduce background. The sys-tematic variation in the branching ratio, that has been observed in variousexperiments [10], may have been caused by a line in the ambient backgroundfrom the 238U decay chain (352 keV, 214Pb). This line is clearly seen in thespectrum (see Fig. 2 right-hand side).TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 233Fig. 2. Left-hand side: 21Na β decay scheme. The experiment aims to determinethe fraction f ending in the 5/2+ state. Right-hand side: Observed γ-ray spectra:(a) total spectrum in coincident with β decay; (b) Compton suppressed spectrumof (a); (c) Compton suppressed background spectrum.3. Cooling stagesIn order to perform precision measurements, radioactive ions producedand separated from the primary beam and unwanted products need to becooled and trapped in atom traps. The cooling procedure needs to be fastand efficient in view of the short lifetime of isotopes. For light isotopessuch as 21Na, the high energy and fully stripped secondary beam passesthrough several cooling stages before it can be delivered as a low energyand singly charged ion beam with acceptable emittance. Neutralization andlaser trapping is the last step to collect radioactive atoms in a well definedcold atomic cloud.3.1. Ion CatcherThe main principle of an Ion Catcher is to stop high-energy ions inmatter, i.e. in a gas or a solid. Electronic stopping causes fast slowing. Inorder to extract a low energy ion beam at the end of the ion catching process,the particles must remain ionized. Neutralization of atoms is a poisoningprocess which must be avoided. The commonly used techniques includegas-filled ion catchers and thermal ionizing devices.Gas-filled ion catcher: Collisions and charge exchange processes bringions to lower energies and charge states as long as they move trough thegas. At low energies, re-ionization and neutralization are in competition.234 M. SohaniCross sections of these processes are highly dependent on the energy of theions and the relative ionization potential of the particle and the stoping gas.There are two strategies: one either relies on the survival of the particlesas singly charged ions or on active re-ionization after neutralization. In thelatter case extraction can be done e.g. after resonant laser ionization [12].Principally, the gas-filled ion catcher can only work when the space chargebuilt up during stopping does not hinder the extraction optics. Therefore,the efficiency for this device depends on the input ion rate [12, 13].Thermal ionizer: A device consists of one or several metal foils thatstop the beam. Atoms will diffuse out of the foils particularly at high tem-perature. Collisions with the surface of the foils and the cavity body canionize these atoms. A potential electric field allows to extract ions. Choosingproper material such as W for the stopping foils and the cavity is important.The difference between the ionization potential of the beam element and thefoil element determines the ionization probability and re-neutralization aftereach collision with the surface. Therefore, a thermal ionizer mainly worksfor alkali and alkali-earth elements that have low ionization potential [14].Investigations for both types of devices were performed in the frameworkof the TRIµP program. Because of the priority of the experiments on Naand Ra isotopes, a thermal ionizer is under the construction and will betested soon. A stack of W foils at high temperature has been chosen asstopper inside a hot W cavity.3.2. RFQ cooler and buncherA segmented radio frequency quadrupole cooler and buncher is the sec-ond stage of the cooling procedure in the TRIµP facility. Input ions comingfrom the thermal ionizer have an energy spread of order several eV. In thefirst part of the RFQ, they pass through a low-pressure gas-filled medium.A longitudinal drag voltage guides them to the exit while confined at thesame time in the transverse direction by a set of radio frequency electricquadrupoles [11]. The second part of the RFQ collects ions in a Paul-trap.By switching the last electrode of the trap, a bunch of ions can be releasedand sent to the atom traps through an electrostatic low-energy beam line.The TRIµP RFQ has been constructed and is commissioned. Measuringthe transmission of the ions and optimizing the settings are the main issuesof the commissioning.3.3. Atomic trapThe β decay experiments at the TRIµP facility will be carried out usinga set of two subsequent magneto-optical traps. The first trap is to collectatoms and bunch them toward the second trap inside a detection chamber.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 235The first trap is made of a small glass cavity and has wide laser beams forefficient collection of atoms. It will contain a hot Yttrium foil to neutralizethe incoming ion beam. The second trap is located in a precision measure-ment chamber that is serving as a reaction microscope, composed of therecoil ion and beta-electron counters.4. β decay spectroscopyCorrelations between particles from β decay manifest the symmetriesand symmetry violations of the weak interaction [15, 16]. In weak interac-tions (a current–current interaction) several currents can contribute. Theseare Scalar (S), Vector (V), Axial-vector (A) and Tensor (T) currents. Inthe Standard Model (SM), the weak interaction is exclusively the result ofV and A currents. The V current is observed in Fermi (F) decay and theA current in Gamow–Teller (GT) decay. Contribution of other currents inβ decay will affect the correlations between the particles and their kinemat-ics. Deviations from the standard V–A model indicates physics beyond theSM.It is not practical to measure the ν particle in β–ν correlations. There-fore, one measures the correlation between the β-electron and recoil ionin order to measure the complete phase-space of the β decay. Recoil-Ion-Momentum Spectroscopy (RIMS) is an advanced method to measure therecoil ion. This method is used at KVI to study charge exchange processwith the recoil energy of the order of eV [17,18]. In RIMS the recoil ions areprojected with an electric field on a position sensitive microchannel platedetector (MCP) (Fig. 3). This method has been used successfully by othergroups for β decay studies [9, 19]. The time of flight measurement of therecoil ion is started by observing a hit in the β-detector and is stopped bythe hit on the MCP. Together with the position of the recoil ion on the MCP,this provides information about the initial momentum. A position sensitiveβ-detector allows to restrict the momentum of the β-electron.Fig. 3. Recoil-Ion-Momentum Spectroscopy sketch.236 M. SohaniThe differential rate of β decay is proportional to the 3-body phase-space and the week interaction matrix element. The general derivation ofthe matrix element (Eq. (1)) shows all the possible correlations between theparticles [20].d2WdΩedΩν ∼ 1 + ap · q̂E+ b ΓmeE+ 〈J〉 ·[ApE+ B q̂ + Dp × q̂E]+ 〈σ〉 ·[GpE+ Q 〈J〉 + R 〈J〉 ×pE], (1)where p and q are momentum of the β-electron and the neutrino, 〈J〉 and〈σ〉 are polarization of the parent nuclei and the β-electron and E is theenergy of the β-electron. a, b,A,B,D,G,Q and R coefficients depend onthe fundamental weak coupling constants and nuclear matrix elements. TheD and R coefficients are zero if time reversal symmetry is conserved. Ex-perimental searching for finite value of the D and R coefficients requires asample of polarized nuclei (〈J〉 6= 0). For the R coefficient also measuring thepolarization of the electrons is required. We aim primarily at measuring D.In the initial studies without polarization, measuring a and b coefficient ex-plores the effect of the non-SM weak currents. In general, there are two freeparameters out of 9 parameters for the 3-body phase-space, including allthe conservation laws and geometrical symmetries for non-polarized atoms.Therefore, one can choose any pair of the parameters to explore the β decay(a) (b)Fig. 4. An event distribution according to a MC simulation of energy of the recoilion versus energy of the β-particle. (a) distribution for 21Na β decay. (b) differencein the distribution for a 1% smaller value of a as compared to the SM prediction.The sensitivity to a is largest for β energies around 1 MeV and recoil ion energiesaround 0.2 MeV.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 237events with a 2D histogram. One choice uses the energy of the recoil ionand the β-particle as free parameters to express all the other parametersin terms of these two. A deviation of a from the SM prediction results ina change in the corresponding distribution as showed in Fig. 4.5. Outlook and conclusionThe TRIµP facility is a user facility to deliver radioactive beams and toperform precision measurements. The TRIµP production target and the sep-arator are functioning. A first user experiment has been already completed.Several experiments using a clean radioactive beam have been requested.This work was supported by the Dutch Stichting vor Fundamenteel On-derzoek der Materie (FOM) under programme 48 (TRIµP) and the EU RTDnetwork NIPNET, HPRI-2001-50034.REFERENCES[1] The TRIµP group contributing to this work: G.P. Berg, S. De, S. Dean,O.C. Dermois, U. Dammalapati, P. Dendooven, K. Jungmann, C.J.G. On-derwater, A. Rogachevskiy, M. Sohani, E. Traykov, A. Mol, L. Willmann,H.W. Wilschut.[2] NuPECC Report available from http://www.nupecc.org/pub/.[3] K. Jungmann, Nucl. Phys. A751, 87c (2005).[4] H.W. Wilschut, Hyperfine Interactions 146/147, 77 (2003).[5] K. Jungmann, in Spin 2004, Eds. K. Aulenbacher, T. Bradamante, A. Bressan,A. Matini, World Scientific, Singapure 2005, p. 108.[6] A.R. Young, M. Boswell, G.P. Berg, A. Rogachevskiy, M. Sohani, E. Traykov,KVI Annual Report 2004, p. 17.[7] G.P.A. Berg, O.C. Dermois, U. Dammalapati, P. Dendooven, M.N. Harakeh,K. Jungmann, C.J.G. Onderwater, A. Rogachevskiy, M. Sohani, E. Traykov,L.Willmann, H.W. Wilschut, submited to Nucl. Instrum. Methodsnucl-ex/0509013.[8] L. Achouri, J.-C. Angélique, G. Ban, G.P.A. Berg, B. Blank, G. Canchel,P.G. Dendooven, J. Giovinazzo, K. Jungman, E. Liénard, I. Matea, O. Navilat-Cuncic, N. Orr, A. Rogachevskiy, M. Sohani, E. Traykov, H.W. Wilschut, KVIExperiment P01 and Annual Report 2004, p. 11.[9] N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, P.A. Vetter, Phys. Rev. Lett. 93,102501 (2004).[10] See e.g. D.E. Alburger, Phys. Rev. C9, 991 (1974); H.S. Wilson et al., Phys.Rev. C22, 1696 (1980).238 M. Sohani[11] See e.g. M.D. Lunney, R.B. Moore, International Journal of Mass Spectrom-etry 190/191, 153 (1999).[12] M. Huyse et al., Nucl. Instrum. Methods B187, 535 (2002).[13] D.J. Morrissey, private communication.[14] R. Kirchner, Nucl. Instum. Methods A292, 203 (1990).[15] H.W. Wilschut, AIP Conferance Proceedings 802, 223 (2005).[16] N. Severijns, M. Beck, O. Naviliat-Cunicic, submited to Rev. Mod. Phys.[17] J.W. Turkstra, R. Hoekstra, S. Knoop, D. Meyer, R. Morgenstern, R.E. Olson,Phys. Rev. Lett. 87, 123202 (2001).[18] S. Knoop, M. Keim, H.J. Lüdde, T. Kirchner, R. Morgenstern, R. Hoekstra,J. Phys. B: At. Mol. Opt. Phys. 38, 3163 (2005).[19] A. Gorelov et al., Phys. Rev. Lett. 94, 132501 (2005).[20] J.D. Jackson, S.B. Treiman, H.W. Wyld, Phys. Lett. 106, 517 (1957).

   University of GroningenTRI mu P - A new facility to produce and trap radioactive isotopesSohani, M; TRImuP GrpPublished in:Acta Physica Polonica BIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2006Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Sohani, M., & TRImuP Grp (2006). TRI mu P - A new facility to produce and trap radioactive isotopes. ActaPhysica Polonica B, 37(1), 231-238.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 07-06-2022Vol. 37 (2006) ACTA PHYSICA POLONICA B No 1TRIµP — A NEW FACILITYTO PRODUCE AND TRAP RADIOACTIVE ISOTOPES∗M. Sohanifor the TRIµP group [1]Kernfysisch Vensneller InstituutZernikelaan 25, 9747 AA Groningen, The Netherlands(Received November 23, 2005)At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a newfacility (TRIµP) is under development. It aims for producing, slowingdown, and trapping of radioactive isotopes in order to perform accuratemeasurements on fundamental symmetries and interactions. A productiontarget station and a dual magnetic separator installed and commissioned.We will slow down the isotopes of interest using an ion catcher and ina further stage a radiofrequency quadropole gas cooler (RFQ). The isotopeswill finally be trapped in an atomic trap for precision studies.PACS numbers: 25.70.–z, 25.70.Mn, 29.70.–h, 32.80.Pj1. IntroductionRare and short lived radioactive isotopes are of interest because theycan offer unique possibilities for investigating fundamental physical symme-tries [2]. Fundamental symmetries are at the basis of the Standard Model(SM). Using radioactive isotopes, limits for the validity of the SM can beexplored in high precision measurements. In particular, high accuracy canbe achieved, when suitable radioactive isotopes are stored in atom or iontraps [3, 4].The TRIµP (Trapped Radioactive Isotopes: µicrolaboratories for fun-damental Physics) facility at the Kernfysisch Vensneller Instituut (KVI) inGroningen, The Netherlands, is being developed to conduct such high pre-cision studies. The local group concentrates on precision measurements ofnuclear β decays [5] and search for permanent electric dipole moments [5].We will briefly describe the complete facility consisting of a production tar-get, a Magnetic Separator with cooling stages and atom traps. We willdescribe also the method of the precision measurements in β decay studies.∗ Presented at the XXIX Mazurian Lakes Conference on PhysicsAugust 30–September 6, 2005, Piaski, Poland.(231)232 M. Sohani2. Magnetic separatorHeavy-ion beams from the superconducting cyclotron AGOR at KVIare used to produce a wide range of products (Fig. 1). A hydrogen gastarget cooled to liquid nitrogen temperature [6] and various solid targetshave been employed in different types of reactions, from fusion evaporationto charge exchange. Using inverse kinematics, products are selected by thedual magnetic separator [7].Fig. 1. Layout of the TRIµP separator.The TRIµP separator has been commissioned. The experiments included21Na production using 21Ne (43MeV/n and 20MeV/n). Typical rates were3×103/s/pnA for 21Na. Recently 104 /s/pnA for 19Ne and 103/s/pnA 20Nawas achieved. In a first physics experiment 21Na and 22Mg were used tomeasure branching ratio of 21Na β decay to the excited state and of 21Neat 350 keV [8]. The population of this state is of relevance for β–ν cor-relation measurements [9]. A stack of two silicon detectors registered theincoming particles and the subsequent β decay. A set of Ge detectors de-tected the γ ray emission following part of the β decays. The Ge Cloverdetectors include a BGO Compton-shield to reduce background. The sys-tematic variation in the branching ratio, that has been observed in variousexperiments [10], may have been caused by a line in the ambient backgroundfrom the 238U decay chain (352 keV, 214Pb). This line is clearly seen in thespectrum (see Fig. 2 right-hand side).TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 233Fig. 2. Left-hand side: 21Na β decay scheme. The experiment aims to determinethe fraction f ending in the 5/2+ state. Right-hand side: Observed γ-ray spectra:(a) total spectrum in coincident with β decay; (b) Compton suppressed spectrumof (a); (c) Compton suppressed background spectrum.3. Cooling stagesIn order to perform precision measurements, radioactive ions producedand separated from the primary beam and unwanted products need to becooled and trapped in atom traps. The cooling procedure needs to be fastand efficient in view of the short lifetime of isotopes. For light isotopessuch as 21Na, the high energy and fully stripped secondary beam passesthrough several cooling stages before it can be delivered as a low energyand singly charged ion beam with acceptable emittance. Neutralization andlaser trapping is the last step to collect radioactive atoms in a well definedcold atomic cloud.3.1. Ion CatcherThe main principle of an Ion Catcher is to stop high-energy ions inmatter, i.e. in a gas or a solid. Electronic stopping causes fast slowing. Inorder to extract a low energy ion beam at the end of the ion catching process,the particles must remain ionized. Neutralization of atoms is a poisoningprocess which must be avoided. The commonly used techniques includegas-filled ion catchers and thermal ionizing devices.Gas-filled ion catcher: Collisions and charge exchange processes bringions to lower energies and charge states as long as they move trough thegas. At low energies, re-ionization and neutralization are in competition.234 M. SohaniCross sections of these processes are highly dependent on the energy of theions and the relative ionization potential of the particle and the stoping gas.There are two strategies: one either relies on the survival of the particlesas singly charged ions or on active re-ionization after neutralization. In thelatter case extraction can be done e.g. after resonant laser ionization [12].Principally, the gas-filled ion catcher can only work when the space chargebuilt up during stopping does not hinder the extraction optics. Therefore,the efficiency for this device depends on the input ion rate [12, 13].Thermal ionizer: A device consists of one or several metal foils thatstop the beam. Atoms will diffuse out of the foils particularly at high tem-perature. Collisions with the surface of the foils and the cavity body canionize these atoms. A potential electric field allows to extract ions. Choosingproper material such as W for the stopping foils and the cavity is important.The difference between the ionization potential of the beam element and thefoil element determines the ionization probability and re-neutralization aftereach collision with the surface. Therefore, a thermal ionizer mainly worksfor alkali and alkali-earth elements that have low ionization potential [14].Investigations for both types of devices were performed in the frameworkof the TRIµP program. Because of the priority of the experiments on Naand Ra isotopes, a thermal ionizer is under the construction and will betested soon. A stack of W foils at high temperature has been chosen asstopper inside a hot W cavity.3.2. RFQ cooler and buncherA segmented radio frequency quadrupole cooler and buncher is the sec-ond stage of the cooling procedure in the TRIµP facility. Input ions comingfrom the thermal ionizer have an energy spread of order several eV. In thefirst part of the RFQ, they pass through a low-pressure gas-filled medium.A longitudinal drag voltage guides them to the exit while confined at thesame time in the transverse direction by a set of radio frequency electricquadrupoles [11]. The second part of the RFQ collects ions in a Paul-trap.By switching the last electrode of the trap, a bunch of ions can be releasedand sent to the atom traps through an electrostatic low-energy beam line.The TRIµP RFQ has been constructed and is commissioned. Measuringthe transmission of the ions and optimizing the settings are the main issuesof the commissioning.3.3. Atomic trapThe β decay experiments at the TRIµP facility will be carried out usinga set of two subsequent magneto-optical traps. The first trap is to collectatoms and bunch them toward the second trap inside a detection chamber.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 235The first trap is made of a small glass cavity and has wide laser beams forefficient collection of atoms. It will contain a hot Yttrium foil to neutralizethe incoming ion beam. The second trap is located in a precision measure-ment chamber that is serving as a reaction microscope, composed of therecoil ion and beta-electron counters.4. β decay spectroscopyCorrelations between particles from β decay manifest the symmetriesand symmetry violations of the weak interaction [15, 16]. In weak interac-tions (a current–current interaction) several currents can contribute. Theseare Scalar (S), Vector (V), Axial-vector (A) and Tensor (T) currents. Inthe Standard Model (SM), the weak interaction is exclusively the result ofV and A currents. The V current is observed in Fermi (F) decay and theA current in Gamow–Teller (GT) decay. Contribution of other currents inβ decay will affect the correlations between the particles and their kinemat-ics. Deviations from the standard V–A model indicates physics beyond theSM.It is not practical to measure the ν particle in β–ν correlations. There-fore, one measures the correlation between the β-electron and recoil ionin order to measure the complete phase-space of the β decay. Recoil-Ion-Momentum Spectroscopy (RIMS) is an advanced method to measure therecoil ion. This method is used at KVI to study charge exchange processwith the recoil energy of the order of eV [17,18]. In RIMS the recoil ions areprojected with an electric field on a position sensitive microchannel platedetector (MCP) (Fig. 3). This method has been used successfully by othergroups for β decay studies [9, 19]. The time of flight measurement of therecoil ion is started by observing a hit in the β-detector and is stopped bythe hit on the MCP. Together with the position of the recoil ion on the MCP,this provides information about the initial momentum. A position sensitiveβ-detector allows to restrict the momentum of the β-electron.Fig. 3. Recoil-Ion-Momentum Spectroscopy sketch.236 M. SohaniThe differential rate of β decay is proportional to the 3-body phase-space and the week interaction matrix element. The general derivation ofthe matrix element (Eq. (1)) shows all the possible correlations between theparticles [20].d2WdΩedΩν ∼ 1 + ap · q̂E+ b ΓmeE+ 〈J〉 ·[ApE+ B q̂ + Dp × q̂E]+ 〈σ〉 ·[GpE+ Q 〈J〉 + R 〈J〉 ×pE], (1)where p and q are momentum of the β-electron and the neutrino, 〈J〉 and〈σ〉 are polarization of the parent nuclei and the β-electron and E is theenergy of the β-electron. a, b,A,B,D,G,Q and R coefficients depend onthe fundamental weak coupling constants and nuclear matrix elements. TheD and R coefficients are zero if time reversal symmetry is conserved. Ex-perimental searching for finite value of the D and R coefficients requires asample of polarized nuclei (〈J〉 6= 0). For the R coefficient also measuring thepolarization of the electrons is required. We aim primarily at measuring D.In the initial studies without polarization, measuring a and b coefficient ex-plores the effect of the non-SM weak currents. In general, there are two freeparameters out of 9 parameters for the 3-body phase-space, including allthe conservation laws and geometrical symmetries for non-polarized atoms.Therefore, one can choose any pair of the parameters to explore the β decay(a) (b)Fig. 4. An event distribution according to a MC simulation of energy of the recoilion versus energy of the β-particle. (a) distribution for 21Na β decay. (b) differencein the distribution for a 1% smaller value of a as compared to the SM prediction.The sensitivity to a is largest for β energies around 1 MeV and recoil ion energiesaround 0.2 MeV.TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 237events with a 2D histogram. One choice uses the energy of the recoil ionand the β-particle as free parameters to express all the other parametersin terms of these two. A deviation of a from the SM prediction results ina change in the corresponding distribution as showed in Fig. 4.5. Outlook and conclusionThe TRIµP facility is a user facility to deliver radioactive beams and toperform precision measurements. The TRIµP production target and the sep-arator are functioning. A first user experiment has been already completed.Several experiments using a clean radioactive beam have been requested.This work was supported by the Dutch Stichting vor Fundamenteel On-derzoek der Materie (FOM) under programme 48 (TRIµP) and the EU RTDnetwork NIPNET, HPRI-2001-50034.REFERENCES[1] The TRIµP group contributing to this work: G.P. Berg, S. De, S. Dean,O.C. Dermois, U. Dammalapati, P. Dendooven, K. Jungmann, C.J.G. On-derwater, A. Rogachevskiy, M. Sohani, E. Traykov, A. Mol, L. Willmann,H.W. Wilschut.[2] NuPECC Report available from http://www.nupecc.org/pub/.[3] K. Jungmann, Nucl. Phys. A751, 87c (2005).[4] H.W. Wilschut, Hyperfine Interactions 146/147, 77 (2003).[5] K. Jungmann, in Spin 2004, Eds. K. Aulenbacher, T. Bradamante, A. Bressan,A. Matini, World Scientific, Singapure 2005, p. 108.[6] A.R. Young, M. Boswell, G.P. Berg, A. Rogachevskiy, M. Sohani, E. Traykov,KVI Annual Report 2004, p. 17.[7] G.P.A. Berg, O.C. Dermois, U. Dammalapati, P. Dendooven, M.N. Harakeh,K. Jungmann, C.J.G. Onderwater, A. Rogachevskiy, M. Sohani, E. Traykov,L.Willmann, H.W. Wilschut, submited to Nucl. Instrum. Methodsnucl-ex/0509013.[8] L. Achouri, J.-C. Angélique, G. Ban, G.P.A. Berg, B. Blank, G. Canchel,P.G. Dendooven, J. Giovinazzo, K. Jungman, E. Liénard, I. Matea, O. Navilat-Cuncic, N. Orr, A. Rogachevskiy, M. Sohani, E. Traykov, H.W. Wilschut, KVIExperiment P01 and Annual Report 2004, p. 11.[9] N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, P.A. Vetter, Phys. Rev. Lett. 93,102501 (2004).[10] See e.g. D.E. Alburger, Phys. Rev. C9, 991 (1974); H.S. Wilson et al., Phys.Rev. C22, 1696 (1980).238 M. Sohani[11] See e.g. M.D. Lunney, R.B. Moore, International Journal of Mass Spectrom-etry 190/191, 153 (1999).[12] M. Huyse et al., Nucl. Instrum. Methods B187, 535 (2002).[13] D.J. Morrissey, private communication.[14] R. Kirchner, Nucl. Instum. Methods A292, 203 (1990).[15] H.W. Wilschut, AIP Conferance Proceedings 802, 223 (2005).[16] N. Severijns, M. Beck, O. Naviliat-Cunicic, submited to Rev. Mod. Phys.[17] J.W. Turkstra, R. Hoekstra, S. Knoop, D. Meyer, R. Morgenstern, R.E. Olson,Phys. Rev. Lett. 87, 123202 (2001).[18] S. Knoop, M. Keim, H.J. Lüdde, T. Kirchner, R. Morgenstern, R. Hoekstra,J. Phys. B: At. Mol. Opt. Phys. 38, 3163 (2005).[19] A. Gorelov et al., Phys. Rev. Lett. 94, 132501 (2005).[20] J.D. Jackson, S.B. Treiman, H.W. Wyld, Phys. Lett. 106, 517 (1957).

University of Groningen Research Database

  
 University of Groningen
TRI mu P - A new facility to produce and trap radioactive isotopes
Sohani, M; TRImuP Grp
Published in:
Acta Physica Polonica B
IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from
it. Please check the document version below.
Document Version
Publisher's PDF, also known as Version of record
Publication date:
2006
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Sohani, M., & TRImuP Grp (2006). TRI mu P - A new facility to produce and trap radioactive isotopes. Acta
Physica Polonica B, 37(1), 231-238.
Copyright
Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the
author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).
Take-down policy
If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately
and investigate your claim.
Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the
number of authors shown on this cover page is limited to 10 maximum.
Download date: 22-05-2019
Vol. 37 (2006) ACTA PHYSICA POLONICA B No 1
TRIµP — A NEW FACILITY
TO PRODUCE AND TRAP RADIOACTIVE ISOTOPES∗
M. Sohani
for the TRIµP group [1]
Kernfysisch Vensneller Instituut
Zernikelaan 25, 9747 AA Groningen, The Netherlands
(Received November 23, 2005)
At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a new
facility (TRIµP) is under development. It aims for producing, slowing
down, and trapping of radioactive isotopes in order to perform accurate
measurements on fundamental symmetries and interactions. A production
target station and a dual magnetic separator installed and commissioned.
We will slow down the isotopes of interest using an ion catcher and in
a further stage a radiofrequency quadropole gas cooler (RFQ). The isotopes
will finally be trapped in an atomic trap for precision studies.
PACS numbers: 25.70.–z, 25.70.Mn, 29.70.–h, 32.80.Pj
1. Introduction
Rare and short lived radioactive isotopes are of interest because they
can offer unique possibilities for investigating fundamental physical symme-
tries [2]. Fundamental symmetries are at the basis of the Standard Model
(SM). Using radioactive isotopes, limits for the validity of the SM can be
explored in high precision measurements. In particular, high accuracy can
be achieved, when suitable radioactive isotopes are stored in atom or ion
traps [3, 4].
The TRIµP (Trapped Radioactive Isotopes: µicrolaboratories for fun-
damental Physics) facility at the Kernfysisch Vensneller Instituut (KVI) in
Groningen, The Netherlands, is being developed to conduct such high pre-
cision studies. The local group concentrates on precision measurements of
nuclear β decays [5] and search for permanent electric dipole moments [5].
We will briefly describe the complete facility consisting of a production tar-
get, a Magnetic Separator with cooling stages and atom traps. We will
describe also the method of the precision measurements in β decay studies.
∗ Presented at the XXIX Mazurian Lakes Conference on Physics
August 30–September 6, 2005, Piaski, Poland.
(231)
232 M. Sohani
2. Magnetic separator
Heavy-ion beams from the superconducting cyclotron AGOR at KVI
are used to produce a wide range of products (Fig. 1). A hydrogen gas
target cooled to liquid nitrogen temperature [6] and various solid targets
have been employed in different types of reactions, from fusion evaporation
to charge exchange. Using inverse kinematics, products are selected by the
dual magnetic separator [7].
Fig. 1. Layout of the TRIµP separator.
The TRIµP separator has been commissioned. The experiments included
21Na production using 21Ne (43MeV/n and 20MeV/n). Typical rates were
3×103/s/pnA for 21Na. Recently 104 /s/pnA for 19Ne and 103/s/pnA 20Na
was achieved. In a first physics experiment 21Na and 22Mg were used to
measure branching ratio of 21Na β decay to the excited state and of 21Ne
at 350 keV [8]. The population of this state is of relevance for β–ν cor-
relation measurements [9]. A stack of two silicon detectors registered the
incoming particles and the subsequent β decay. A set of Ge detectors de-
tected the γ ray emission following part of the β decays. The Ge Clover
detectors include a BGO Compton-shield to reduce background. The sys-
tematic variation in the branching ratio, that has been observed in various
experiments [10], may have been caused by a line in the ambient background
from the 238U decay chain (352 keV, 214Pb). This line is clearly seen in the
spectrum (see Fig. 2 right-hand side).
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 233
Fig. 2. Left-hand side: 21Na β decay scheme. The experiment aims to determine
the fraction f ending in the 5/2+ state. Right-hand side: Observed γ-ray spectra:
(a) total spectrum in coincident with β decay; (b) Compton suppressed spectrum
of (a); (c) Compton suppressed background spectrum.
3. Cooling stages
In order to perform precision measurements, radioactive ions produced
and separated from the primary beam and unwanted products need to be
cooled and trapped in atom traps. The cooling procedure needs to be fast
and efficient in view of the short lifetime of isotopes. For light isotopes
such as 21Na, the high energy and fully stripped secondary beam passes
through several cooling stages before it can be delivered as a low energy
and singly charged ion beam with acceptable emittance. Neutralization and
laser trapping is the last step to collect radioactive atoms in a well defined
cold atomic cloud.
3.1. Ion Catcher
The main principle of an Ion Catcher is to stop high-energy ions in
matter, i.e. in a gas or a solid. Electronic stopping causes fast slowing. In
order to extract a low energy ion beam at the end of the ion catching process,
the particles must remain ionized. Neutralization of atoms is a poisoning
process which must be avoided. The commonly used techniques include
gas-filled ion catchers and thermal ionizing devices.
Gas-filled ion catcher: Collisions and charge exchange processes bring
ions to lower energies and charge states as long as they move trough the
gas. At low energies, re-ionization and neutralization are in competition.
234 M. Sohani
Cross sections of these processes are highly dependent on the energy of the
ions and the relative ionization potential of the particle and the stoping gas.
There are two strategies: one either relies on the survival of the particles
as singly charged ions or on active re-ionization after neutralization. In the
latter case extraction can be done e.g. after resonant laser ionization [12].
Principally, the gas-filled ion catcher can only work when the space charge
built up during stopping does not hinder the extraction optics. Therefore,
the efficiency for this device depends on the input ion rate [12, 13].
Thermal ionizer: A device consists of one or several metal foils that
stop the beam. Atoms will diffuse out of the foils particularly at high tem-
perature. Collisions with the surface of the foils and the cavity body can
ionize these atoms. A potential electric field allows to extract ions. Choosing
proper material such as W for the stopping foils and the cavity is important.
The difference between the ionization potential of the beam element and the
foil element determines the ionization probability and re-neutralization after
each collision with the surface. Therefore, a thermal ionizer mainly works
for alkali and alkali-earth elements that have low ionization potential [14].
Investigations for both types of devices were performed in the framework
of the TRIµP program. Because of the priority of the experiments on Na
and Ra isotopes, a thermal ionizer is under the construction and will be
tested soon. A stack of W foils at high temperature has been chosen as
stopper inside a hot W cavity.
3.2. RFQ cooler and buncher
A segmented radio frequency quadrupole cooler and buncher is the sec-
ond stage of the cooling procedure in the TRIµP facility. Input ions coming
from the thermal ionizer have an energy spread of order several eV. In the
first part of the RFQ, they pass through a low-pressure gas-filled medium.
A longitudinal drag voltage guides them to the exit while confined at the
same time in the transverse direction by a set of radio frequency electric
quadrupoles [11]. The second part of the RFQ collects ions in a Paul-trap.
By switching the last electrode of the trap, a bunch of ions can be released
and sent to the atom traps through an electrostatic low-energy beam line.
The TRIµP RFQ has been constructed and is commissioned. Measuring
the transmission of the ions and optimizing the settings are the main issues
of the commissioning.
3.3. Atomic trap
The β decay experiments at the TRIµP facility will be carried out using
a set of two subsequent magneto-optical traps. The first trap is to collect
atoms and bunch them toward the second trap inside a detection chamber.
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 235
The first trap is made of a small glass cavity and has wide laser beams for
efficient collection of atoms. It will contain a hot Yttrium foil to neutralize
the incoming ion beam. The second trap is located in a precision measure-
ment chamber that is serving as a reaction microscope, composed of the
recoil ion and beta-electron counters.
4. β decay spectroscopy
Correlations between particles from β decay manifest the symmetries
and symmetry violations of the weak interaction [15, 16]. In weak interac-
tions (a current–current interaction) several currents can contribute. These
are Scalar (S), Vector (V), Axial-vector (A) and Tensor (T) currents. In
the Standard Model (SM), the weak interaction is exclusively the result of
V and A currents. The V current is observed in Fermi (F) decay and the
A current in Gamow–Teller (GT) decay. Contribution of other currents in
β decay will affect the correlations between the particles and their kinemat-
ics. Deviations from the standard V–A model indicates physics beyond the
SM.
It is not practical to measure the ν particle in β–ν correlations. There-
fore, one measures the correlation between the β-electron and recoil ion
in order to measure the complete phase-space of the β decay. Recoil-Ion-
Momentum Spectroscopy (RIMS) is an advanced method to measure the
recoil ion. This method is used at KVI to study charge exchange process
with the recoil energy of the order of eV [17,18]. In RIMS the recoil ions are
projected with an electric field on a position sensitive microchannel plate
detector (MCP) (Fig. 3). This method has been used successfully by other
groups for β decay studies [9, 19]. The time of flight measurement of the
recoil ion is started by observing a hit in the β-detector and is stopped by
the hit on the MCP. Together with the position of the recoil ion on the MCP,
this provides information about the initial momentum. A position sensitive
β-detector allows to restrict the momentum of the β-electron.
Fig. 3. Recoil-Ion-Momentum Spectroscopy sketch.
236 M. Sohani
The differential rate of β decay is proportional to the 3-body phase-
space and the week interaction matrix element. The general derivation of
the matrix element (Eq. (1)) shows all the possible correlations between the
particles [20].
d2W
dΩe
dΩν ∼ 1 + a
p · qˆ
E
+ b Γ
me
E
+ 〈J〉 ·
[
A
p
E
+B qˆ +D
p× qˆ
E
]
+ 〈σ〉 ·
[
G
p
E
+Q 〈J〉 +R 〈J〉 ×
p
E
]
, (1)
where p and q are momentum of the β-electron and the neutrino, 〈J〉 and
〈σ〉 are polarization of the parent nuclei and the β-electron and E is the
energy of the β-electron. a, b,A,B,D,G,Q and R coefficients depend on
the fundamental weak coupling constants and nuclear matrix elements. The
D and R coefficients are zero if time reversal symmetry is conserved. Ex-
perimental searching for finite value of the D and R coefficients requires a
sample of polarized nuclei (〈J〉 6= 0). For the R coefficient also measuring the
polarization of the electrons is required. We aim primarily at measuring D.
In the initial studies without polarization, measuring a and b coefficient ex-
plores the effect of the non-SM weak currents. In general, there are two free
parameters out of 9 parameters for the 3-body phase-space, including all
the conservation laws and geometrical symmetries for non-polarized atoms.
Therefore, one can choose any pair of the parameters to explore the β decay
(a) (b)
Fig. 4. An event distribution according to a MC simulation of energy of the recoil
ion versus energy of the β-particle. (a) distribution for 21Na β decay. (b) difference
in the distribution for a 1% smaller value of a as compared to the SM prediction.
The sensitivity to a is largest for β energies around 1MeV and recoil ion energies
around 0.2MeV.
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 237
events with a 2D histogram. One choice uses the energy of the recoil ion
and the β-particle as free parameters to express all the other parameters
in terms of these two. A deviation of a from the SM prediction results in
a change in the corresponding distribution as showed in Fig. 4.
5. Outlook and conclusion
The TRIµP facility is a user facility to deliver radioactive beams and to
perform precision measurements. The TRIµP production target and the sep-
arator are functioning. A first user experiment has been already completed.
Several experiments using a clean radioactive beam have been requested.
This work was supported by the Dutch Stichting vor Fundamenteel On-
derzoek der Materie (FOM) under programme 48 (TRIµP) and the EU RTD
network NIPNET, HPRI-2001-50034.
REFERENCES
[1] The TRIµP group contributing to this work: G.P. Berg, S. De, S. Dean,
O.C. Dermois, U. Dammalapati, P. Dendooven, K. Jungmann, C.J.G. On-
derwater, A. Rogachevskiy, M. Sohani, E. Traykov, A. Mol, L. Willmann,
H.W. Wilschut.
[2] NuPECC Report available from http://www.nupecc.org/pub/.
[3] K. Jungmann, Nucl. Phys. A751, 87c (2005).
[4] H.W. Wilschut, Hyperfine Interactions 146/147, 77 (2003).
[5] K. Jungmann, in Spin 2004, Eds. K. Aulenbacher, T. Bradamante, A. Bressan,
A. Matini, World Scientific, Singapure 2005, p. 108.
[6] A.R. Young, M. Boswell, G.P. Berg, A. Rogachevskiy, M. Sohani, E. Traykov,
KVI Annual Report 2004, p. 17.
[7] G.P.A. Berg, O.C. Dermois, U. Dammalapati, P. Dendooven, M.N. Harakeh,
K. Jungmann, C.J.G. Onderwater, A. Rogachevskiy, M. Sohani, E. Traykov,
L.Willmann, H.W. Wilschut, submited to Nucl. Instrum. Methods
nucl-ex/0509013.
[8] L. Achouri, J.-C. Angélique, G. Ban, G.P.A. Berg, B. Blank, G. Canchel,
P.G. Dendooven, J. Giovinazzo, K. Jungman, E. Liénard, I. Matea, O. Navilat-
Cuncic, N. Orr, A. Rogachevskiy, M. Sohani, E. Traykov, H.W. Wilschut, KVI
Experiment P01 and Annual Report 2004, p. 11.
[9] N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, P.A. Vetter, Phys. Rev. Lett. 93,
102501 (2004).
[10] See e.g. D.E. Alburger, Phys. Rev. C9, 991 (1974); H.S. Wilson et al., Phys.
Rev. C22, 1696 (1980).
238 M. Sohani
[11] See e.g. M.D. Lunney, R.B. Moore, International Journal of Mass Spectrom-
etry 190/191, 153 (1999).
[12] M. Huyse et al., Nucl. Instrum. Methods B187, 535 (2002).
[13] D.J. Morrissey, private communication.
[14] R. Kirchner, Nucl. Instum. Methods A292, 203 (1990).
[15] H.W. Wilschut, AIP Conferance Proceedings 802, 223 (2005).
[16] N. Severijns, M. Beck, O. Naviliat-Cunicic, submited to Rev. Mod. Phys.
[17] J.W. Turkstra, R. Hoekstra, S. Knoop, D. Meyer, R. Morgenstern, R.E. Olson,
Phys. Rev. Lett. 87, 123202 (2001).
[18] S. Knoop, M. Keim, H.J. Lüdde, T. Kirchner, R. Morgenstern, R. Hoekstra,
J. Phys. B: At. Mol. Opt. Phys. 38, 3163 (2005).
[19] A. Gorelov et al., Phys. Rev. Lett. 94, 132501 (2005).
[20] J.D. Jackson, S.B. Treiman, H.W. Wyld, Phys. Lett. 106, 517 (1957).


  
 University of Groningen
TRIMP - A new facility to produce and trap radioactive isotopes
Sohani, M.; TRImuP Grp
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Acta Physica Polonica B
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Polonica B, 37(1), 231-238.
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Vol. 37 (2006) ACTA PHYSICA POLONICA B No 1
TRIµP — A NEW FACILITY
TO PRODUCE AND TRAP RADIOACTIVE ISOTOPES∗
M. Sohani
for the TRIµP group [1]
Kernfysisch Vensneller Instituut
Zernikelaan 25, 9747 AA Groningen, The Netherlands
(Received November 23, 2005)
At the Kernfysisch Vensneller Institiutr (KVI) in Groningen, NL, a new
facility (TRIµP) is under development. It aims for producing, slowing
down, and trapping of radioactive isotopes in order to perform accurate
measurements on fundamental symmetries and interactions. A production
target station and a dual magnetic separator installed and commissioned.
We will slow down the isotopes of interest using an ion catcher and in
a further stage a radiofrequency quadropole gas cooler (RFQ). The isotopes
will finally be trapped in an atomic trap for precision studies.
PACS numbers: 25.70.–z, 25.70.Mn, 29.70.–h, 32.80.Pj
1. Introduction
Rare and short lived radioactive isotopes are of interest because they
can offer unique possibilities for investigating fundamental physical symme-
tries [2]. Fundamental symmetries are at the basis of the Standard Model
(SM). Using radioactive isotopes, limits for the validity of the SM can be
explored in high precision measurements. In particular, high accuracy can
be achieved, when suitable radioactive isotopes are stored in atom or ion
traps [3, 4].
The TRIµP (Trapped Radioactive Isotopes: µicrolaboratories for fun-
damental Physics) facility at the Kernfysisch Vensneller Instituut (KVI) in
Groningen, The Netherlands, is being developed to conduct such high pre-
cision studies. The local group concentrates on precision measurements of
nuclear β decays [5] and search for permanent electric dipole moments [5].
We will briefly describe the complete facility consisting of a production tar-
get, a Magnetic Separator with cooling stages and atom traps. We will
describe also the method of the precision measurements in β decay studies.
∗ Presented at the XXIX Mazurian Lakes Conference on Physics
August 30–September 6, 2005, Piaski, Poland.
(231)
232 M. Sohani
2. Magnetic separator
Heavy-ion beams from the superconducting cyclotron AGOR at KVI
are used to produce a wide range of products (Fig. 1). A hydrogen gas
target cooled to liquid nitrogen temperature [6] and various solid targets
have been employed in different types of reactions, from fusion evaporation
to charge exchange. Using inverse kinematics, products are selected by the
dual magnetic separator [7].
Fig. 1. Layout of the TRIµP separator.
The TRIµP separator has been commissioned. The experiments included
21Na production using 21Ne (43MeV/n and 20MeV/n). Typical rates were
3×103/s/pnA for 21Na. Recently 104 /s/pnA for 19Ne and 103/s/pnA 20Na
was achieved. In a first physics experiment 21Na and 22Mg were used to
measure branching ratio of 21Na β decay to the excited state and of 21Ne
at 350 keV [8]. The population of this state is of relevance for β–ν cor-
relation measurements [9]. A stack of two silicon detectors registered the
incoming particles and the subsequent β decay. A set of Ge detectors de-
tected the γ ray emission following part of the β decays. The Ge Clover
detectors include a BGO Compton-shield to reduce background. The sys-
tematic variation in the branching ratio, that has been observed in various
experiments [10], may have been caused by a line in the ambient background
from the 238U decay chain (352 keV, 214Pb). This line is clearly seen in the
spectrum (see Fig. 2 right-hand side).
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 233
Fig. 2. Left-hand side: 21Na β decay scheme. The experiment aims to determine
the fraction f ending in the 5/2+ state. Right-hand side: Observed γ-ray spectra:
(a) total spectrum in coincident with β decay; (b) Compton suppressed spectrum
of (a); (c) Compton suppressed background spectrum.
3. Cooling stages
In order to perform precision measurements, radioactive ions produced
and separated from the primary beam and unwanted products need to be
cooled and trapped in atom traps. The cooling procedure needs to be fast
and efficient in view of the short lifetime of isotopes. For light isotopes
such as 21Na, the high energy and fully stripped secondary beam passes
through several cooling stages before it can be delivered as a low energy
and singly charged ion beam with acceptable emittance. Neutralization and
laser trapping is the last step to collect radioactive atoms in a well defined
cold atomic cloud.
3.1. Ion Catcher
The main principle of an Ion Catcher is to stop high-energy ions in
matter, i.e. in a gas or a solid. Electronic stopping causes fast slowing. In
order to extract a low energy ion beam at the end of the ion catching process,
the particles must remain ionized. Neutralization of atoms is a poisoning
process which must be avoided. The commonly used techniques include
gas-filled ion catchers and thermal ionizing devices.
Gas-filled ion catcher: Collisions and charge exchange processes bring
ions to lower energies and charge states as long as they move trough the
gas. At low energies, re-ionization and neutralization are in competition.
234 M. Sohani
Cross sections of these processes are highly dependent on the energy of the
ions and the relative ionization potential of the particle and the stoping gas.
There are two strategies: one either relies on the survival of the particles
as singly charged ions or on active re-ionization after neutralization. In the
latter case extraction can be done e.g. after resonant laser ionization [12].
Principally, the gas-filled ion catcher can only work when the space charge
built up during stopping does not hinder the extraction optics. Therefore,
the efficiency for this device depends on the input ion rate [12, 13].
Thermal ionizer: A device consists of one or several metal foils that
stop the beam. Atoms will diffuse out of the foils particularly at high tem-
perature. Collisions with the surface of the foils and the cavity body can
ionize these atoms. A potential electric field allows to extract ions. Choosing
proper material such as W for the stopping foils and the cavity is important.
The difference between the ionization potential of the beam element and the
foil element determines the ionization probability and re-neutralization after
each collision with the surface. Therefore, a thermal ionizer mainly works
for alkali and alkali-earth elements that have low ionization potential [14].
Investigations for both types of devices were performed in the framework
of the TRIµP program. Because of the priority of the experiments on Na
and Ra isotopes, a thermal ionizer is under the construction and will be
tested soon. A stack of W foils at high temperature has been chosen as
stopper inside a hot W cavity.
3.2. RFQ cooler and buncher
A segmented radio frequency quadrupole cooler and buncher is the sec-
ond stage of the cooling procedure in the TRIµP facility. Input ions coming
from the thermal ionizer have an energy spread of order several eV. In the
first part of the RFQ, they pass through a low-pressure gas-filled medium.
A longitudinal drag voltage guides them to the exit while confined at the
same time in the transverse direction by a set of radio frequency electric
quadrupoles [11]. The second part of the RFQ collects ions in a Paul-trap.
By switching the last electrode of the trap, a bunch of ions can be released
and sent to the atom traps through an electrostatic low-energy beam line.
The TRIµP RFQ has been constructed and is commissioned. Measuring
the transmission of the ions and optimizing the settings are the main issues
of the commissioning.
3.3. Atomic trap
The β decay experiments at the TRIµP facility will be carried out using
a set of two subsequent magneto-optical traps. The first trap is to collect
atoms and bunch them toward the second trap inside a detection chamber.
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 235
The first trap is made of a small glass cavity and has wide laser beams for
efficient collection of atoms. It will contain a hot Yttrium foil to neutralize
the incoming ion beam. The second trap is located in a precision measure-
ment chamber that is serving as a reaction microscope, composed of the
recoil ion and beta-electron counters.
4. β decay spectroscopy
Correlations between particles from β decay manifest the symmetries
and symmetry violations of the weak interaction [15, 16]. In weak interac-
tions (a current–current interaction) several currents can contribute. These
are Scalar (S), Vector (V), Axial-vector (A) and Tensor (T) currents. In
the Standard Model (SM), the weak interaction is exclusively the result of
V and A currents. The V current is observed in Fermi (F) decay and the
A current in Gamow–Teller (GT) decay. Contribution of other currents in
β decay will affect the correlations between the particles and their kinemat-
ics. Deviations from the standard V–A model indicates physics beyond the
SM.
It is not practical to measure the ν particle in β–ν correlations. There-
fore, one measures the correlation between the β-electron and recoil ion
in order to measure the complete phase-space of the β decay. Recoil-Ion-
Momentum Spectroscopy (RIMS) is an advanced method to measure the
recoil ion. This method is used at KVI to study charge exchange process
with the recoil energy of the order of eV [17,18]. In RIMS the recoil ions are
projected with an electric field on a position sensitive microchannel plate
detector (MCP) (Fig. 3). This method has been used successfully by other
groups for β decay studies [9, 19]. The time of flight measurement of the
recoil ion is started by observing a hit in the β-detector and is stopped by
the hit on the MCP. Together with the position of the recoil ion on the MCP,
this provides information about the initial momentum. A position sensitive
β-detector allows to restrict the momentum of the β-electron.
Fig. 3. Recoil-Ion-Momentum Spectroscopy sketch.
236 M. Sohani
The differential rate of β decay is proportional to the 3-body phase-
space and the week interaction matrix element. The general derivation of
the matrix element (Eq. (1)) shows all the possible correlations between the
particles [20].
d2W
dΩe
dΩν ∼ 1 + a
p · qˆ
E
+ b Γ
me
E
+ 〈J〉 ·
[
A
p
E
+B qˆ +D
p× qˆ
E
]
+ 〈σ〉 ·
[
G
p
E
+Q 〈J〉 +R 〈J〉 ×
p
E
]
, (1)
where p and q are momentum of the β-electron and the neutrino, 〈J〉 and
〈σ〉 are polarization of the parent nuclei and the β-electron and E is the
energy of the β-electron. a, b,A,B,D,G,Q and R coefficients depend on
the fundamental weak coupling constants and nuclear matrix elements. The
D and R coefficients are zero if time reversal symmetry is conserved. Ex-
perimental searching for finite value of the D and R coefficients requires a
sample of polarized nuclei (〈J〉 6= 0). For the R coefficient also measuring the
polarization of the electrons is required. We aim primarily at measuring D.
In the initial studies without polarization, measuring a and b coefficient ex-
plores the effect of the non-SM weak currents. In general, there are two free
parameters out of 9 parameters for the 3-body phase-space, including all
the conservation laws and geometrical symmetries for non-polarized atoms.
Therefore, one can choose any pair of the parameters to explore the β decay
(a) (b)
Fig. 4. An event distribution according to a MC simulation of energy of the recoil
ion versus energy of the β-particle. (a) distribution for 21Na β decay. (b) difference
in the distribution for a 1% smaller value of a as compared to the SM prediction.
The sensitivity to a is largest for β energies around 1MeV and recoil ion energies
around 0.2MeV.
TRIµP — a New Facility to Produce and Trap Radioactive Isotopes 237
events with a 2D histogram. One choice uses the energy of the recoil ion
and the β-particle as free parameters to express all the other parameters
in terms of these two. A deviation of a from the SM prediction results in
a change in the corresponding distribution as showed in Fig. 4.
5. Outlook and conclusion
The TRIµP facility is a user facility to deliver radioactive beams and to
perform precision measurements. The TRIµP production target and the sep-
arator are functioning. A first user experiment has been already completed.
Several experiments using a clean radioactive beam have been requested.
This work was supported by the Dutch Stichting vor Fundamenteel On-
derzoek der Materie (FOM) under programme 48 (TRIµP) and the EU RTD
network NIPNET, HPRI-2001-50034.
REFERENCES
[1] The TRIµP group contributing to this work: G.P. Berg, S. De, S. Dean,
O.C. Dermois, U. Dammalapati, P. Dendooven, K. Jungmann, C.J.G. On-
derwater, A. Rogachevskiy, M. Sohani, E. Traykov, A. Mol, L. Willmann,
H.W. Wilschut.
[2] NuPECC Report available from http://www.nupecc.org/pub/.
[3] K. Jungmann, Nucl. Phys. A751, 87c (2005).
[4] H.W. Wilschut, Hyperfine Interactions 146/147, 77 (2003).
[5] K. Jungmann, in Spin 2004, Eds. K. Aulenbacher, T. Bradamante, A. Bressan,
A. Matini, World Scientific, Singapure 2005, p. 108.
[6] A.R. Young, M. Boswell, G.P. Berg, A. Rogachevskiy, M. Sohani, E. Traykov,
KVI Annual Report 2004, p. 17.
[7] G.P.A. Berg, O.C. Dermois, U. Dammalapati, P. Dendooven, M.N. Harakeh,
K. Jungmann, C.J.G. Onderwater, A. Rogachevskiy, M. Sohani, E. Traykov,
L.Willmann, H.W. Wilschut, submited to Nucl. Instrum. Methods
nucl-ex/0509013.
[8] L. Achouri, J.-C. Angélique, G. Ban, G.P.A. Berg, B. Blank, G. Canchel,
P.G. Dendooven, J. Giovinazzo, K. Jungman, E. Liénard, I. Matea, O. Navilat-
Cuncic, N. Orr, A. Rogachevskiy, M. Sohani, E. Traykov, H.W. Wilschut, KVI
Experiment P01 and Annual Report 2004, p. 11.
[9] N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, P.A. Vetter, Phys. Rev. Lett. 93,
102501 (2004).
[10] See e.g. D.E. Alburger, Phys. Rev. C9, 991 (1974); H.S. Wilson et al., Phys.
Rev. C22, 1696 (1980).
238 M. Sohani
[11] See e.g. M.D. Lunney, R.B. Moore, International Journal of Mass Spectrom-
etry 190/191, 153 (1999).
[12] M. Huyse et al., Nucl. Instrum. Methods B187, 535 (2002).
[13] D.J. Morrissey, private communication.
[14] R. Kirchner, Nucl. Instum. Methods A292, 203 (1990).
[15] H.W. Wilschut, AIP Conferance Proceedings 802, 223 (2005).
[16] N. Severijns, M. Beck, O. Naviliat-Cunicic, submited to Rev. Mod. Phys.
[17] J.W. Turkstra, R. Hoekstra, S. Knoop, D. Meyer, R. Morgenstern, R.E. Olson,
Phys. Rev. Lett. 87, 123202 (2001).
[18] S. Knoop, M. Keim, H.J. Lüdde, T. Kirchner, R. Morgenstern, R. Hoekstra,
J. Phys. B: At. Mol. Opt. Phys. 38, 3163 (2005).
[19] A. Gorelov et al., Phys. Rev. Lett. 94, 132501 (2005).
[20] J.D. Jackson, S.B. Treiman, H.W. Wyld, Phys. Lett. 106, 517 (1957).


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