We present results from two recent runs which illustrate the performance of the PRISMA spectrometer in the proximity of the upper limit of its operational interval, namely 96Zr + 124Sn at Elab = 500 MeV and 136Xe + 208Pb at Elab = 930 MeV. In the latter run, the γ array CLARA also allowed us to identify previously unknown γ transitions in the nuclides 136Cs and 134I

Beghini, S.

Chapman, R.

Corradi, L.

Farnea, E.

Fioretto, E.

Freeman, S.

Gadea, A.

Guiot, B.

Hodsdon, A.

Jones, G.

Labiche, M.

Mason, P.

Mengoni, D.

Montagnoli, G.

Mărginean, N.

Napoli, D.R.

O'Donnell, D.

Ollier, J.

Orlandi, R.

Pollarolo, G.

Recchia, F.

Sahin, E.

Scarlassara, F.

Silvestri, R.

Smith, J.

Spohr, K.

Stefanini, A.M.

Szilner, S.

Thompson, N.

Ur, C.A.

Valiente-Dobón, J.J.

Wady, P.

Wang, Z.

English

Enlighten: Publications

  
 
 
 
Mason, P. et al. (2009) Exploring the performance of the spectrometer 
prisma in heavy zirconium and xenon mass regions. Acta Physica Polonica 
B, 40 (3). pp. 489-492. ISSN 0587-4254 
 
Copyright © 2009 Jagellonian University 
 
 
 
http://eprints.gla.ac.uk/94471/ 
 
 
 
 
Deposited on:  16 June 2014 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Enlighten – Research publications by members of the University of Glasgow 
http://eprints.gla.ac.uk 
Vol. 40 (2009) ACTA PHYSICA POLONICA B No 3
EXPLORING THE PERFORMANCE
OF THE SPECTROMETER PRISMA IN HEAVY
ZIRCONIUM AND XENON MASS REGIONS∗
P. Masona, L. Corradia, E. Fiorettoa, B. Guiota, R. Silvestria
A.M. Stefaninia, S. Beghinib, G. Montagnolib, F. Scarlassarab
N. Mărgineanc, S. Szilnerd, G. Pollaroloe, E. Farneab
A. Gadeaa, D. Mengonib, D.R. Napolia, F. Recchiab, E. Sahina
C.A. Urb, J.J. Valiente-Dobóna, R. Chapmanf , S. Freemanh
A. Hodsdonf , G. Jones9, M. Labicheg, D. O’Donnellg, J. Ollierg
R. Orlandif , J. Smithf , K. Spohrf , N. Thompsoni
P. Wadyf , Z. Wangf
aINFN, Laboratori Nazionali di Legnaro, Italy
bINFN and University of Padova, Italy
cHoria Hulubei National Institute, Bucharest, Romania
dRuder Boskovic Institute, Zagreb, Croatia
eINFN and University of Torino, Italy
fUniversity of West of Scotland, Paisley, UK
gDaresbury Laboratory, Daresbury, UK
hUniversity of Manchester, Manchester, UK
iUniversity of Surrey, Guildford, UK
(Received October 30, 2008)
We present results from two recent runs which illustrate the perfor-
mance of the PRISMA spectrometer in the proximity of the upper limit
of its operational interval, namely 96Zr+124Sn at Elab = 500 MeV and
136Xe+208Pb at Elab = 930 MeV. In the latter run, the γ array CLARA
also allowed us to identify previously unknown γ transitions in the nuclides
136Cs and 134I.
PACS numbers: 23.20.Lv, 25.70.Hi, 29.30.Aj
1. Introduction
Multinucleon transfer processes in the proximity of the Coulomb barrier
represent an efficient means to populate nuclei moderately far from stability
and non-yrast states that may be hardly reached through fusion–evaporation
∗ Presented at the Zakopane Conference on Nuclear Physics, September 1–7, 2008,
Zakopane, Poland.
(489)
490 P. Mason et al.
reactions [1]. This holds in particular in the region of neutron-rich isotopes of
elements Z = 30–60, which can be accessed basically only through peripheral
collisions between heavy ions or actinide fission. In either case, direct iden-
tification of the reaction products represents a challenging issue, because of
the huge number of nuclear species populated in the process and the needed
Z- and A-resolutions. In fact, nuclear-structure and reaction-dynamics stud-
ies that use peripheral collisions in the proximity of the Coulomb barrier,
were recently boosted by the coupling of efficient γ arrays to large solid-
angle magnetic spectrometers. The high efficiency and selectivity of the
PRISMA–CLARA set-up [2, 3], along with the availability of such beams
as 96Zr and 136Xe delivered by the TANDEM–ALPI and PIAVE–ALPI ac-
celerator complexes at LNL at energies up to ∼7 MeVA and intensities up
to ∼5 pnA, allowed us over the last years to perform several experiments
aimed at the exploration of nuclear structure and reaction dynamics in a
region ranging from Z ≃ 8 to Z ≃ 60. We here focus on two runs which
well illustrate PRISMA’s performance in the proximity of the upper limit of
its operational interval, namely 96Zr+124Sn at Elab = 500 MeV and
136Xe
+ 208Pb at Elab=930 MeV.
2. Experimental setup and experimental results
The spectrometer has been described in Refs. [2, 4–7], its foremost fea-
tures being the large solid-angle and momentum acceptance (∼ 80 msr and
∆p/p = ±10%, respectively). At its entrance is placed a two-dimensional
position-sensitive micro-channel plate detector providing a start signal for
time-of-flight (TOF) measurement and Xi, Yi position signals. After a path
of ∼ 6.5 m, ions hit the focal-plane detector, which consists of a ten-section
multiwire-type parallel plate providing timing (TOF stop) signals and Xf ,Yf
coordinates; this detector is followed by a transverse-field four-stage ioniza-
tion chamber (IC), which gives the total energy (E) of the ion and its nuclear
charge. The γ-ray array CLARA consisted of 24 HPGe clover-type detectors
in a 2pi configuration at the target point. The total photopeak efficiency of
this array was ∼ 3% for Eγ = 1.33 MeV; its energy resolution was ∼ 0.8%
after Doppler correction.
The identification of ejectiles in nuclear charge and mass performed by
PRISMA is respectively based on the measurement of energy loss in the IC
and the reconstruction of trajectory of the ejectile through the spectrometer,
which is in turn based on the measurement of the space coordinates Xi,Yi
and Xf ,Yf . In particular, trajectory reconstruction yields the total distance
D traveled by the ion (and therefore its scalar velocity v = D/TOF) and
the curvature radius R of its trajectory inside the dipole magnet: from v
Exploring the Performance of the Spectrometer PRISMA in Heavy . . . 491
Z=42
Z=41
Z=40
Z=33
Z=32
Z=31
Z=30
Z=34
Z=38
Z=37
Z=36
Z=35
Z=39
2·106
6·106
1·107
2·104
6·104
1·105
1.4·105
4·103
1.2·104
2·104
2.8·104
5·104
1.5·105
2.5·105
2·104
1·105
1.8·105
5·103
2.5·104
4.5·104
4·103
1.2·104
2·104
1·103
5·103
9·103
1·103
3·103
5·103
4·102
1.2·103
2·103
2.8·103
4·102
1.2·103
2·103
2·102
1·103
1.8·103
2·102
6·102
1·103
1.4·103
Co
un
ts
60 70 80 90 100 110
Mass [a.m.u.]
Z=55
Z=56
Z=57
1.0·103
3.0·103
5.0·103
7.0·103
Co
un
ts

5.0·102
1.5·103
2.5·103
3.5·103
2.0·102
6.0·102
1.0·103
124 128 132 136
Mass [a.m.u.]
140 144 148
Eγ=262 keV
Eγ [keV]
Eγ=1399 keV
136Cs
134IEγ=952 keV
20
60
100
2
6
10
14
200 400 600 800 1000 1200 1400
Co
un
ts

Fig. 1. (Left-hand side) Mass spectra of elements Z = 30–42 produced in the
reaction 96Zr+124Sn at Elab = 50MeV and detected at the angle θlab=38
◦. (Right-
hand side) (Top) Mass spectra of elements Z = 55–57 produced in the reaction
136Xe+208Pb at Elab = 930 MeV and detected at the angle θlab=38
◦. (Bottom) γ
spectra respectively tagged on the detection of the nuclides 136Cs and 134I, produced
in the reaction 136Xe+208Pb. The Doppler correction is applied on the basis of the
vector velocity of the ejectile. Previously unknown transitions are identified.
492 P. Mason et al.
and R, the ratio A/q is determined as
A
q
=
e
mnc
BdR
β
√
1− β2 ,
where q is the atomic charge state of the ejectile, mn is the atomic-mass
unity, Bd is the magnetic field in the dipole and β = v/c. The separation
of atomic charge states is achieved by plotting a matrix of the quantity
Rv
√
1− β2 versus the total energy E (≃ Av2/2) measured by the IC. The
mass spectra of the nuclides produced in the reactions 96Zr+124Sn at Elab =
500 MeV and 136Xe+208Pb at Elab = 930 MeV are plotted in Fig. 1, along
with γ spectra tagged on specific nuclides produced in the latter reaction.
The resolutions are respectively ∆A/A ≃ 1/190 and 1/200, allowing a good
isotopic separation.
3. Outlook
Numerous neutron-rich nuclides in the proximity of 96Zr and 136Xe were
populated in the reactions 96Zr+124Sn at Elab = 500 MeV and
136Xe+208Pb
at E = 930 MeV. The good beam stability and high intrinsic efficiency of
PRISMA’s detectors for zirconium- and xenon-like ions (∼ 80%) allowed
the collection of high-statistics data-sets that look very promising both on
the side of nuclear structure (the analysis of γ–γ coincidences from previous
thick-target experiments performed with large γ arrays may benefit from
the unambiguous attribution of new transitions to specific nuclides) and on
the side of reaction dynamics (the high number of collected PRISMA–γ and
PRISMA–γ–γ coincidences may make possible a quantitative study of the
impact of neutron evaporation on the final mass yields and/or a quantitative
study of mutual excitation of the reaction partners). The interpretation of
experimental results is under way.
REFERENCES
[1] R. Broda, J. Phys. G 32, R151 (2006).
[2] A.M. Stefanini et al., Nucl. Phys. A701, 217c (2002).
[3] A. Gadea et al., Eur. Phys. J. A20, 193 (2004).
[4] G. Montagnoli et al., Nucl. Instrum. Methods Phys. Res. A547, 455 (2005).
[5] S. Beghini et al., Nucl. Instrum. Methods Phys. Res. A551, 364 (2005).
[6] S. Szilner et al., Phys. Rev. C76, 024604 (2007).
[7] P. Mason et al., Eur. Phys. J. ST 150, 359 (2007).


Exploring the performance of the spectrometer prisma in heavy zirconium and xenon mass regions

Mason, P

Stefanini, A. M.

Mãrginean, N.

Napoli, D. R.

Valiente Dobóna, J. J.

MONTAGNOLI, GIOVANNA

SCARLASSARA, FERNANDO

SZILNER, SUZANA

FARNEA, ENRICO

MENGONI, DANIELE

RECCHIA, FRANCESCO

UR, CALIN ALEXANDRU

Archivio istituzionale della ricerca - Università di Padova

We present results from two recent runs which illustrate the performance of the PRISMA spectrometer in the proximity of the upper limit of its operational interval, namely 96Zr+124Sn at Elab = 500 MeV and 136Xe+208Pb at Elab = 930 MeV. In the latter run, the γ array CLARA also allowed us to identify previously unknown γ transitions in the nuclides 136Cs and 134I

Mãrginean, N.

Ur, C. A.

Valiente-Dobóna, J. J.

The University of Manchester - Institutional Repository

Enlighten

     Mason, P. et al. (2009) Exploring the performance of the spectrometer prisma in heavy zirconium and xenon mass regions. Acta Physica Polonica B, 40 (3). pp. 489-492. ISSN 0587-4254  Copyright © 2009 Jagellonian University    http://eprints.gla.ac.uk/94471/     Deposited on:  16 June 2014                           Enlighten – Research publications by members of the University of Glasgow http://eprints.gla.ac.uk Vol. 40 (2009) ACTA PHYSICA POLONICA B No 3EXPLORING THE PERFORMANCEOF THE SPECTROMETER PRISMA IN HEAVYZIRCONIUM AND XENON MASS REGIONS∗P. Masona, L. Corradia, E. Fiorettoa, B. Guiota, R. SilvestriaA.M. Stefaninia, S. Beghinib, G. Montagnolib, F. ScarlassarabN. Mărgineanc, S. Szilnerd, G. Pollaroloe, E. FarneabA. Gadeaa, D. Mengonib, D.R. Napolia, F. Recchiab, E. SahinaC.A. Urb, J.J. Valiente-Dobóna, R. Chapmanf , S. FreemanhA. Hodsdonf , G. Jones9, M. Labicheg, D. O’Donnellg, J. OlliergR. Orlandif , J. Smithf , K. Spohrf , N. ThompsoniP. Wadyf , Z. WangfaINFN, Laboratori Nazionali di Legnaro, ItalybINFN and University of Padova, ItalycHoria Hulubei National Institute, Bucharest, RomaniadRuder Boskovic Institute, Zagreb, CroatiaeINFN and University of Torino, ItalyfUniversity of West of Scotland, Paisley, UKgDaresbury Laboratory, Daresbury, UKhUniversity of Manchester, Manchester, UKiUniversity of Surrey, Guildford, UK(Received October 30, 2008)We present results from two recent runs which illustrate the perfor-mance of the PRISMA spectrometer in the proximity of the upper limitof its operational interval, namely 96Zr+124Sn at Elab = 500 MeV and136Xe+208Pb at Elab = 930 MeV. In the latter run, the γ array CLARAalso allowed us to identify previously unknown γ transitions in the nuclides136Cs and 134I.PACS numbers: 23.20.Lv, 25.70.Hi, 29.30.Aj1. IntroductionMultinucleon transfer processes in the proximity of the Coulomb barrierrepresent an efficient means to populate nuclei moderately far from stabilityand non-yrast states that may be hardly reached through fusion–evaporation∗ Presented at the Zakopane Conference on Nuclear Physics, September 1–7, 2008,Zakopane, Poland.(489)490 P. Mason et al.reactions [1]. This holds in particular in the region of neutron-rich isotopes ofelements Z = 30–60, which can be accessed basically only through peripheralcollisions between heavy ions or actinide fission. In either case, direct iden-tification of the reaction products represents a challenging issue, because ofthe huge number of nuclear species populated in the process and the neededZ- and A-resolutions. In fact, nuclear-structure and reaction-dynamics stud-ies that use peripheral collisions in the proximity of the Coulomb barrier,were recently boosted by the coupling of efficient γ arrays to large solid-angle magnetic spectrometers. The high efficiency and selectivity of thePRISMA–CLARA set-up [2, 3], along with the availability of such beamsas 96Zr and 136Xe delivered by the TANDEM–ALPI and PIAVE–ALPI ac-celerator complexes at LNL at energies up to ∼7 MeVA and intensities upto ∼5 pnA, allowed us over the last years to perform several experimentsaimed at the exploration of nuclear structure and reaction dynamics in aregion ranging from Z ≃ 8 to Z ≃ 60. We here focus on two runs whichwell illustrate PRISMA’s performance in the proximity of the upper limit ofits operational interval, namely 96Zr+124Sn at Elab = 500 MeV and136Xe+ 208Pb at Elab=930 MeV.2. Experimental setup and experimental resultsThe spectrometer has been described in Refs. [2, 4–7], its foremost fea-tures being the large solid-angle and momentum acceptance (∼ 80 msr and∆p/p = ±10%, respectively). At its entrance is placed a two-dimensionalposition-sensitive micro-channel plate detector providing a start signal fortime-of-flight (TOF) measurement and Xi, Yi position signals. After a pathof ∼ 6.5 m, ions hit the focal-plane detector, which consists of a ten-sectionmultiwire-type parallel plate providing timing (TOF stop) signals and Xf ,Yfcoordinates; this detector is followed by a transverse-field four-stage ioniza-tion chamber (IC), which gives the total energy (E) of the ion and its nuclearcharge. The γ-ray array CLARA consisted of 24 HPGe clover-type detectorsin a 2pi configuration at the target point. The total photopeak efficiency ofthis array was ∼ 3% for Eγ = 1.33 MeV; its energy resolution was ∼ 0.8%after Doppler correction.The identification of ejectiles in nuclear charge and mass performed byPRISMA is respectively based on the measurement of energy loss in the ICand the reconstruction of trajectory of the ejectile through the spectrometer,which is in turn based on the measurement of the space coordinates Xi,Yiand Xf ,Yf . In particular, trajectory reconstruction yields the total distanceD traveled by the ion (and therefore its scalar velocity v = D/TOF) andthe curvature radius R of its trajectory inside the dipole magnet: from vExploring the Performance of the Spectrometer PRISMA in Heavy . . . 491Z=42Z=41Z=40Z=33Z=32Z=31Z=30Z=34Z=38Z=37Z=36Z=35Z=392·1066·1061·1072·1046·1041·1051.4·1054·1031.2·1042·1042.8·1045·1041.5·1052.5·1052·1041·1051.8·1055·1032.5·1044.5·1044·1031.2·1042·1041·1035·1039·1031·1033·1035·1034·1021.2·1032·1032.8·1034·1021.2·1032·1032·1021·1031.8·1032·1026·1021·1031.4·103Counts60 70 80 90 100 110Mass [a.m.u.]Z=55Z=56Z=571.0·1033.0·1035.0·1037.0·103Counts5.0·1021.5·1032.5·1033.5·1032.0·1026.0·1021.0·103124 128 132 136Mass [a.m.u.]140 144 148Eγ=262 keVEγ [keV]Eγ=1399 keV136Cs134IEγ=952 keV2060100261014200 400 600 800 1000 1200 1400CountsFig. 1. (Left-hand side) Mass spectra of elements Z = 30–42 produced in thereaction 96Zr+124Sn at Elab = 50MeV and detected at the angle θlab=38◦. (Right-hand side) (Top) Mass spectra of elements Z = 55–57 produced in the reaction136Xe+208Pb at Elab = 930 MeV and detected at the angle θlab=38◦. (Bottom) γspectra respectively tagged on the detection of the nuclides 136Cs and 134I, producedin the reaction 136Xe+208Pb. The Doppler correction is applied on the basis of thevector velocity of the ejectile. Previously unknown transitions are identified.492 P. Mason et al.and R, the ratio A/q is determined asAq=emncBdRβ√1− β2 ,where q is the atomic charge state of the ejectile, mn is the atomic-massunity, Bd is the magnetic field in the dipole and β = v/c. The separationof atomic charge states is achieved by plotting a matrix of the quantityRv√1− β2 versus the total energy E (≃ Av2/2) measured by the IC. Themass spectra of the nuclides produced in the reactions 96Zr+124Sn at Elab =500 MeV and 136Xe+208Pb at Elab = 930 MeV are plotted in Fig. 1, alongwith γ spectra tagged on specific nuclides produced in the latter reaction.The resolutions are respectively ∆A/A ≃ 1/190 and 1/200, allowing a goodisotopic separation.3. OutlookNumerous neutron-rich nuclides in the proximity of 96Zr and 136Xe werepopulated in the reactions 96Zr+124Sn at Elab = 500 MeV and136Xe+208Pbat E = 930 MeV. The good beam stability and high intrinsic efficiency ofPRISMA’s detectors for zirconium- and xenon-like ions (∼ 80%) allowedthe collection of high-statistics data-sets that look very promising both onthe side of nuclear structure (the analysis of γ–γ coincidences from previousthick-target experiments performed with large γ arrays may benefit fromthe unambiguous attribution of new transitions to specific nuclides) and onthe side of reaction dynamics (the high number of collected PRISMA–γ andPRISMA–γ–γ coincidences may make possible a quantitative study of theimpact of neutron evaporation on the final mass yields and/or a quantitativestudy of mutual excitation of the reaction partners). The interpretation ofexperimental results is under way.REFERENCES[1] R. Broda, J. Phys. G 32, R151 (2006).[2] A.M. Stefanini et al., Nucl. Phys. A701, 217c (2002).[3] A. Gadea et al., Eur. Phys. J. A20, 193 (2004).[4] G. Montagnoli et al., Nucl. Instrum. Methods Phys. Res. A547, 455 (2005).[5] S. Beghini et al., Nucl. Instrum. Methods Phys. Res. A551, 364 (2005).[6] S. Szilner et al., Phys. Rev. C76, 024604 (2007).[7] P. Mason et al., Eur. Phys. J. ST 150, 359 (2007).

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Exploring the performance of the spectrometer prisma in heavy zirconium and xenon mass regions

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