Transfer reactions have provided exciting opportunities to study the
structure of exotic nuclei and are often used to inform studies relating to
nucleosynthesis and applications. In order to benefit from these reactions and
their application to rare ion beams (RIBs) it is necessary to develop the tools
and techniques to perform and analyze the data from reactions performed in
inverse kinematics, that is with targets of light nuclei and heavier beams. We
are continuing to expand the transfer reaction toolbox in preparation for the
next generation of facilities, such as the Facility for Rare Ion Beams (FRIB),
which is scheduled for completion in 2022. An important step in this process is
to perform the (d,n) reaction in inverse kinematics, with analyses that include
Q-value spectra and differential cross sections. In this way, proton-transfer
reactions can be placed on the same level as the more commonly used
neutron-transfer reactions, such as (d,p), (9Be,8Be), and (13C,12C). Here we
present an overview of the techniques used in (d,p) and (d,n), and some recent
data from (d,n) reactions in inverse kinematics using stable beams of 12C and
16O.Comment: 9 pages, 4 figures, presented at the XXXV Mazurian Lakes Conference
  on Physics, Piaski, Polan

Allen, J.

Atencio, A.

Bardayan, D. W.

Blankstein, D.

Burcher, S.

Carter, A. B.

Chipps, K. A.

Cizewski, J. A.

Cox, I.

Elledge, Z.

Febbraro, M.

Fijalkowska, A.

Grzywacz, R.

Hall, M. R.

Jones, K. L.

King, T. T.

Lepailleur, A.

Madurga, M.

Marley, S. T.

O'Malley, P. D.

Pain, S. D.

Paulauskas, S. V.

Peters, W. A.

Reingold, C.

Smith, K.

Tan, W.

Taylor, S.

Thornsberry, C.

Vostinar, M.

Walter, D.

Acta Physica Polonica B

English

arXiv

Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs), it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the (d; n) reaction in inverse kinematics, with analyses that include Q-value spectra and differential cross sections. In this way, proton-Transfer reactions can be placed on the same level as the more commonly used neutron-Transfer reactions, such as (d; p), (9Be,8Be), and (13C,12C). Here, we present an overview of the techniques used in (d; p) and (d; n), and some recent data from (d; n) reactions in inverse kinematics using stable beams of 12C and 16O

Fijałkowska, A.

O\u27malley, P. D.

LSU Scholarly Repository (Louisiana State Univ.)

Louisiana State University LSU Scholarly Repository Faculty Publications Department of Physics & Astronomy 3-1-2018 Development of the (d; n) proton-Transfer reaction in inverse kinematics for structure studies K. L. Jones The University of Tennessee, Knoxville C. Thornsberry The University of Tennessee, Knoxville J. Allen University of Notre Dame A. Atencio Rutgers University–New Brunswick D. W. Bardayan University of Notre Dame See next page for additional authors Follow this and additional works at: https://repository.lsu.edu/physics_astronomy_pubs Recommended Citation Jones, K., Thornsberry, C., Allen, J., Atencio, A., Bardayan, D., Blankstein, D., Burcher, S., Carter, A., Chipps, K., Cizewski, J., Cox, I., Elledge, Z., Febbraro, M., Fijałkowska, A., Grzywacz, R., Hall, M., King, T., Lepailleur, A., Madurga, M., Marley, S., O'malley, P., Paulauskas, S., Pain, S., Peters, W., Reingold, C., Smith, K., Taylor, S., Tan, W., Vostinar, M., & Walter, D. (2018). Development of the (d; n) proton-Transfer reaction in inverse kinematics for structure studies. Acta Physica Polonica B, 49 (3), 365-372. https://doi.org/10.5506/APhysPolB.49.365 This Conference Proceeding is brought to you for free and open access by the Department of Physics & Astronomy at LSU Scholarly Repository. It has been accepted for inclusion in Faculty Publications by an authorized administrator of LSU Scholarly Repository. For more information, please contact ir@lsu.edu. Authors K. L. Jones, C. Thornsberry, J. Allen, A. Atencio, D. W. Bardayan, D. Blankstein, S. Burcher, A. B. Carter, K. A. Chipps, J. A. Cizewski, I. Cox, Z. Elledge, M. Febbraro, A. Fijałkowska, R. Grzywacz, M. R. Hall, T. T. King, A. Lepailleur, M. Madurga, S. T. Marley, P. D. O'malley, S. V. Paulauskas, S. D. Pain, W. A. Peters, C. Reingold, K. Smith, S. Taylor, W. Tan, M. Vostinar, and D. Walter This conference proceeding is available at LSU Scholarly Repository: https://repository.lsu.edu/physics_astronomy_pubs/3062 Development of the (d,n) proton-transfer reactionin inverse kinematics for structure studies∗K.L. Jonesa, C. Thornsberrya, J. Allenb, A. Atencioc,D.W. Bardayanb, D. Blanksteinb, S. Burchera, A.B. Cartera,K.A. Chippsd, J.A. Cizewskic, I. Coxa, Z. Elledgea,M. Febbrarod, A. Fija lkowskac, R. Grzywacza, M.R. Hallb,T.T. Kinga, A. Lepailleurc, M. Madurgaa, S.T. Marleye,P.D. O’Malleyb, S.V. Paulauskasa, S.D. Paind, W.A. Petersf ,C. Reingoldb, K. Smitha †, S. Taylora, W. Tanb, M. Vostinara,D. WaltercaDepartment of Physics and Astronomy, University of Tennessee, Knoxville,TN 37996, USAbDepartment of Physics, University of Notre Dame, Notre Dame, IN 46556, USAcDepartment of Physics and Astronomy, Rutgers University, New Brunswick,NJ 08903, USAdPhysics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USAeDepartment. of Physics Louisiana State University, USAfJoint Institute for Nuclear Physics and Applications, Oak Ridge, TN 37831, USATransfer reactions have provided exciting opportunities to study thestructure of exotic nuclei and are often used to inform studies relating tonucleosynthesis and applications. In order to benefit from these reactionsand their application to rare ion beams (RIBs) it is necessary to developthe tools and techniques to perform and analyze the data from reactionsperformed in inverse kinematics, that is with targets of light nuclei andheavier beams. We are continuing to expand the transfer reaction toolboxin preparation for the next generation of facilities, such as the Facility forRare Ion Beams (FRIB), which is scheduled for completion in 2022. Animportant step in this process is to perform the (d,n) reaction in inversekinematics, with analyses that include Q-value spectra and differential crosssections. In this way, proton-transfer reactions can be placed on the samelevel as the more commonly used neutron-transfer reactions, such as (d,p),(9Be,8Be), and (13C,12C). Here we present an overview of the techniques∗ Presented at the XXXV Mazurian Lakes Conference on Physics, Piaski, Poland,September 3-9, 2017† Current address: Los Alamos National Laboratory, Los Alamos, NM 87545, USA(1)arXiv:1712.06944v1  [nucl-ex]  19 Dec 20172 Mazurian-Kate printed on December 20, 2017used in (d,p) and (d,n), and some recent data from (d,n) reactions in inversekinematics using stable beams of 12C and 16O.PACS numbers: 25.60.Je, 29.38.Gj, 21.10.Pc, 21.10.Jx, 25.45.Hi1. Introduction: Deuteron-induced transfer reactionsDeuteronProton and neutron;Tensor force brings togetherfragile building block.Transfer reactions can be used to elucidate the structure of nuclei throughmeasurements of the Q-value of the reaction, and the intensity and shapeof angular distributions of particles emerging from the reaction. When rareion beams (RIBs) undergo transfer reactions on targets of light ions, com-monly referred to as inverse kinematics measurements (see Fig. 1), thestructure of exotic nuclei can be studied in detail. The first neutron trans-fer reactions performed in inverse kinematics used stable 132,136Xe beamsat the Gesellschaft für Schwerionenforschung (GSI) [1]. This pioneering ex-periment laid the groundwork for many neutron transfer studies performedwith RIBs since the mid-1990s, in particular using the (d,p) single-neutrontransfer reaction.Fig. 1. Cartoon of a (d,p) reaction in inverse kinematics. A RIB impinges on adeuteron target resulting in a residual nucleus and a proton. Adapted from Ref. [2]Mazurian-Kate printed on December 20, 2017 3The Q-value of a (d,p) reaction is extracted from the measured angleand energy of the proton. The conversion from the laboratory to the center-of-mass frame causes kinematic compression of the spectrum of states in theresidual nucleus. However, in most cases the limiting factor in the resolu-tion is the CD2 target thickness, and commonly targets of 100 - 200 µg/cm2are used in order to resolve individual states, while still achieving statisticalsignificance. Thicker targets can be used when states are identified fromtheir γ decays (see for example Refs. [3–8]), but in this case the statisticaluncertainty is often limited by the efficiency of the γ-ray detector system.The shapes of the angular distributions of protons emitted from (d,p)reactions can be indicative of the ` transfer of the reaction. The sensitivityof the angular distributions to the transferred ` is dependent on the beamenergy, with very low or very high beam energies (compared to the energy ofthe Coulomb barrier) producing fairly flat angular distributions, regardlessof ` transfer.Another quantity of interest that can be extracted from transfer reac-tions is the spectroscopic factor, S, which is connected to the structure ofthe nucleus through the single-particle radial overlap function u`sj and thenormalized wave function, v`sj :S`sj = |A`sj |2 (1)where A`sj is the spectroscopic amplitude, and:u`sj(r) = A`sjv`sj(r). (2)However, as S is extracted from a measured normalized differential cross-section and an angular distribution calculated from a reaction model:Sexp =dσexp/dΩdσcalc/dΩ(3)S is not an observable of the experiment and is model dependent. The mainsources of uncertainty in the calculations come from the optical (scattering)potentials and the bound state potential in the final state. Optical poten-tials can be extracted by fitting elastic scattering data. Different opticalpotentials can produce angular distributions with both different shapes andintensities. As for the bound state of the residual nucleus, this is typicallymodeled by a Woods-Saxon potential with the depth adjusted to the bindingenergy of the state, and the geometry defined by the radius and diffuseness.At beam energies close to the Coulomb barrier the magnitudes of the cal-culated differential cross sections can be very sensitive to the bound-statepotential used.4 Mazurian-Kate printed on December 20, 20172. The (d,n) single proton transfer reactionIn stark contrast to the recent growth in inverse kinematics (d,p) mea-surements, there have been fewer developments made for the (d,n) single-proton transfer reaction, in particular where the nuclear structure is ex-tracted from measuring the emitted neutrons (see for example [9–11]). Ourcollaboration has been developing techniques for performing the (d,n) pro-ton transfer reaction with RIBs using the Versatile Array of Neutron Detec-tors at Low Energy (VANDLE) [12, 13]. The energy and angle of protonsemitted from (d,p) reactions can be measured with relative ease in sili-con detectors. It is less straightforward to measure the energy of neutronsemerging from (d,n) reactions. VANDLE uses the time of flight of neutronsto find their kinetic energy. However, the plastic scintillator from whichVANDLE is built is also sensitive to γ rays, which can cause a limitingsource of background in RIB experiments.Our first attempt to measure states in 8B using the 7Be(d,n)8B reaction,at the TWINSOL facility at the University of Notre Dame [14], sufferedfrom excessive levels of background in the neutron spectra. This was due inpart to the configuration where the VANDLE bars were in the direct path ofneutrons and γ rays emitted from the RIB source in TWINSOL. A measure-ment made in the same experimental campaign utilizing the 17F(d,n)18Nereaction produced results from deuterated liquid scintillator detectors [15]where pulse-shape discrimination (PSD) was used to separate neutrons fromγ rays. This largely eliminated the background issues. However, a limita-tion in this technique is the requirement that neutrons deposit energy abovea threshold of about 100 keVee before PSD separation can be achieved. Forcomparison, in the analysis presented below the threshold for VANDLEwas set at 30 keVee, allowing neutrons with energies down to 300 keV tobe measured. As the most interesting region of the angular distribution isat backward angles in the laboratory frame where the neutrons have thelowest energies, this threshold can severely limit the PSD technique. Liq-uid neutron detectors can still be used in as TOF detectors below neutronenergies of about 1 MeV.Ideally, these reactions would be performed in a configuration wherethe detectors are shielded from both the neutrons and the γ rays emanatingfrom the production target, the beam dump would not be directly viewed bythe detectors, and the room would have low levels of background radiation.In most cases it is necessary to tag on the reaction of interest, usually by re-quiring an increase in charge of the recoil by one unit compared to the beamspecies. As the recoil cone is small and forward focussed this requires usingMazurian-Kate printed on December 20, 2017 5a detector system that has Z-discrimination and can take the full beamrate. Options include phoswich (phosphor sandwich detectors), ionizationchambers, magnetic recoil separators, and time-of-flight setups. The choiceof recoil detector depends on the specifics of the experiment, namely thebeam rate and the ∆Z/Z (i.e. 1/Z), the latter of which is straightforwardfor light nuclei, but becomes increasingly stringent for heavier elements.Since these first attempts at 7Be(d,n)8B and 17F(d,n)18Ne measure-ments, there have been significant upgrades to TWINSOL, with more shield-ing between the source and the experimental area [16]. At the same time,the production efficiency has been increased by reducing the thickness ofthe gas cell windows, and the ion optics have been improved to provide asmaller beam spot. Additionally, recoil identification detectors will aid inchannel selection to reduce background in future VANDLE measurementswith RIBs.3. Inverse Kinematics (d,n) reactions with stable beamsA stable beam experiment was run at the Nuclear Structure Laboratory(NSL) at the University of Notre Dame in preparation for future TWINSOLexperiments and to investigate the response of VANDLE to inverse kinemat-ics (d,n) reactions where signal-to-noise levels are more optimal than withRIBs and the level of statistics is not limiting. A total of 21 VANDLEdetectors were mounted, at a distance of 0.5 m from a deuterated polyethy-lene (CD2) target, at laboratory angles from 65◦ to 170◦. The stop signalfor the time of flight (ToF) was provided by the delayed RF signal fromthe sweeper/buncher after the FN tandem. The bunches came at 100 nsintervals. The beams used were 12C, at 8 energy steps between 18.5 and41.7 MeV, and 16O at 64 MeV. A 413 µg/cm2 CD2 target was used for bothbeams, a second, thicker 711 µg/cm2 CD2 target was used for the12C beam.In total, approximately 2 hours of beam were used for the 8 energy stepswith the 12C beam, and an hour for the 16O. The beam intensities were 4 -5 enA in each case, which represents about 1-5 × 109 pps.Fig. 2 shows the type of spectra seen online from just a few minutesof beam, 16O in this case. Each detector covered approximately 5◦ in thelaboratory frame, with the most backward angles, from 170◦, at the bottomof the figure. The two vertical lines, where all detectors fired at the sameToF regardless of angle, are the γ flashes from the target and the beam stop.The target γ flash was used as a timing reference for measuring the kineticenergy of the neutrons. The two loci relating to the proton-transfer to the6 Mazurian-Kate printed on December 20, 2017Fig. 2. Detector number versus corrected time of flight for neutrons following the16O(d,n)17F reaction, in inverse kinematics, at E16O = 64 MeV. The polar anglein the laboratory frame increases with decreasing detector number. The detectorscovered a range from 65◦ to 170◦ in the laboratory frame. The two vertical linesat 0 ns and 10 ns are from the flashes of γ rays emitted as the beam struck thetarget and the beam stop, respectively.ground and first excited states in 17F traverse the plot from the top left,close to the beam stop γ flash toward the bottom right, where the intensityfades to around that of the background.Fig. 3 shows the same information, but for the 12C(d,n)13N reaction,after the conversion of the neutron ToF into energy and detector numberinto the laboratory angle. The ground state population is seen as a locussweeping across from the top-center of the plot toward the lower right. Asin inverse kinematics (d,p) measurements, the emergent particle has higherenergies at forward angles and low energies at backward angles.The data for each beam at each beam energy were subdivided by polarangle of the neutron in the center-of-mass frame. The intensity of each statewas found by fitting a gaussian curve on a linear background, as shown inFig. 4. These fits were made on the neutron ToF spectra as the resolutionis linear, as apposed to neutron energy spectra where the resolution goesMazurian-Kate printed on December 20, 2017 7Lab Angle (deg)60 80 100 120 140 160Neutron Energy (MeV)0.511.522.533.544.5505001000150020002500Energy vs. Lab AngleN13C(d,n)12N*13C(d,n)12Fig. 3. Angle versus energy plot for neutrons following the 12C(d,n)13N reaction,in inverse kinematics, at E12C = 41.7 MeV. The loci show the population of theground state and an excited state at 2.365 MeV. Smoothing related to the widthof each detector was applied in the calculation of the polar angle.as ToF2. These intensities can then be plotted versus center-of-mass an-gle to produce angular distributions. A normalization was performed usingthe known target thickness and the beam intensity, monitored by a cur-rent integrator connected to an electrically insulated brass beam stop. Thedifferential cross sections are currently being finalized and are beyond thescope of this contribution. Those that have been analyzed are of sufficientquality to make meaningful comparisons with previous data and state-of-the-art theory.4. OutlookThe (d,p) reaction has been used extensively in inverse kinematics sincethe mid-1990’s, thus allowing transfer reaction techniques to be performedon beams of exotic nuclei. This has proven to be a powerful method forextracting spectroscopic information relating to single-neutron states awayfrom stability. In order to study single-proton states in an analogous way itis necessary to develop techniques relating to the (d,n) single-proton trans-fer reaction. Our collaboration performed the (d,n) reaction on beams of8 Mazurian-Kate printed on December 20, 2017Neutron TOF (ns)20 40 60 80 100Counts per Bin01002003004005006007008009001000Corrected TOF vs. LocationFit FunctionNeutron PeakBackgroundNext Target Gamma-FlashBeamstop Gamma-FlashFig. 4. Neutron time-of-flight spectrum for the 12C(d,n)13N reaction at θCM = 12◦(θlab = 144◦), in inverse kinematics, with a beam energy of E12C = 41.7 MeV. Thegaussian fit to the peak for population of the ground state, the background, andthe sum fit function are shown in green, magenta, and red respectively. The timingof the γ flash from the next beam pulse is shown.stable 12C and 16O with the neutron ToF array VANDLE. High quality datahave been extracted from these measurements and normalized differentialcross-sections are currently being finalized.Channel selection is important to VANDLE measurements with RIBs,where backgrounds from both neutrons and γ rays are often limiting. Cur-rently we are developing a compact ionization chamber with an internalscintillator to provide a tag on the Z of the recoil. The scintillator willbe instrumented with silicon photomultipliers. The results presented herefrom stable beam measurements are encouraging and provide motivation todevelop recoil particle identification detectors such that the (d,n) reaction,measured with ToF detector arrays, can be used as a spectroscopic tool withRIBs.Mazurian-Kate printed on December 20, 2017 9AcknowledgmentsThis research was supported in part by the U.S. Department of En-ergy, Office of Science, Office of Nuclear Physics under Contract No. DE-FG02-96ER40963 (UT), DE-AC05-00OR22725 (ORNL), by the NationalScience Foundation under Contract No. PHY1713857 (ND), PHY0354870and PHY1404218 (Rutgers). This research was sponsored in part by theNational Nuclear Security Administration under the Stewardship ScienceAcademic Alliance program through DOE Cooperative Agreement No. de-na0002132 (Rutgers and UTK). STM would like to acknowledge fundingfrom the Louisiana State University Department of Physics and Astronomy.REFERENCES[1] G. Kraus et al., Z. Phys. A340, 339 (1991).[2] K.L. Jones, Phys. Scr. T152, 014020 (2013).[3] M. Labiche et al., Nucl. Instr. and Meth. in Phys. Res. A614, 439 (2010).[4] J. Simpson et al., Acta Physica Hungarica 11, 159 (2000).[5] V. Bildstein et al., Prog. in Part. and Nucl. Phys. 59, 386 (2007).[6] J. Eberth et al., Progress in Particle and Nuclear Physics 46, 389 (2001).[7] C. A. Diget et al., Journal of Instrumentation 6, P02005 (2011).[8] C. Svensson et al., J. Phys. G 31, S1663 (2005).[9] W.A. Peters et al., Bull. Am. Phys. Soc. 58, 29 (2013).[10] M. Febbraro et al., Phys. Rev. C 96, 024613 (2017).[11] L. Baby et al., Nucl.Instr. and Meth. in Phys. Res. A 877, 34 (2018).[12] S.V. Paulauskas et al., Nucl. Instr. and Meth. in Phys. Res. A 737, 22 (2014).[13] W.A. Peters et al., Nucl. Instr. and Meth. in Phys. Res. A836, 122 (2016).[14] F.D. Becchetti et al., Nucl. Instr. and Meth. in Phys. Res. B 376, 397 (2016).[15] M. Febbraro et al., EPJ Web of Conferences 66, 03026 (2014).[16] P.D. O’Malley et al., Nucl. Instr. and Meth. in Phys. Res. B 376, 417 (2016).

Development of the (d; n) proton-Transfer reaction in inverse kinematics for structure studies

K.L. Jones

C. Thornsberry

J. Allen

A. Atencio

D.W. Bardayan

D. Blankstein

S. Burcher

A.B. Carter

K.A. Chipps

J.A. Cizewski

I. Cox

Z. Elledge

M. Febbraro

A. Fijałkowska

R. Grzywacz

M.R. Hall

T.T. King

A. Lepailleur

M. Madurga

S.T. Marley

P.D. O'Malley

S.V. Paulauskas

S.D. Pain

W.A. Peters

C. Reingold

K. Smith

S. Taylor

W. Tan

M. Vostinar

D. Walter

Crossref

Development of the $(d,n)$ Proton-transfer Reaction in Inverse Kinematics for Structure Studies

Development of the (d,n) proton-transfer reaction in inverse kinematics
  for structure studies

Development of the (d,n) proton-transfer reaction in inverse kinematics for structure studies

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