ISOMER SPECTROSCOPY OF 127 Cd

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RESULTS: Singles Gamma Spectra Five gamma energy transitions were observed with energies739 keV, 822 keV , 712 keV 849 keV and 111 keV γ –γ Coincidence Spectra Life time measurement Shell Model calculation predicted the existence of (19/2 + ) isomer of a similar half life in 127Cd . A calculation using the E3 strength of the neighbouring 129 Sn isotone gives similar life time supporting the spin assignment . The energy of 13/2 - state ,obtained in Shell Model calculation is too high compared to the experiment value . Hence, a modification of the monopole interaction used in the calculation is required. EXPERIMENTAL TECHNIQUE: In achromatic mode the fragments with same A/Q ratio are focused at the same position on the final focal plane L ife T ime Analysis 100 1000 10000 0 10000 20000 30000 40000 50000 Tim e [ns ] C ounts/2500[ns] T 1/2 = 17.5(3) µs RISING gamma array 15 Euroball cluster detectors with 7 crystals each Photopeak efficiency ~ 15 % at 1 MeV EXP 48 Cd 79 is a neutron rich nucleus which has 3 neutrons and 2 protons less than the doubly magic 132 Sn . The latter nucleus is a benchmark for nuclear structure investigations. Systematics of the Cd isotope chain shows evolution of neutron single particle energy levels. F.Naqvi, 1,2 M. Górska, 2 L. Cáceres, 2,3 A.Jungclaus, 3 M. Pfützner, 4 H. Grawe, 2 S. Pietri, 2 P. H Regan, 5 D. Rudolph, 6 Z. Podolyák, 5 K. Andgren, 7 T. Beck, 2 B. Bednarczyk, 2,8 J. Benlliure, 9 G. Benzoni, 10 A.M. Bruce, 11 E. Casarejos, 9 B. Cederwall, 7 F. Crespi, 10 P. Detistov, 12 Zs. Dombrádi, 13 P. Doornenbal, 2 H. Geissel, 2 J. Gerl, 2 J. Grębosz, 2,8 B. Hadinia, 7 M. Hellström, 6 R. Hoischen, 2,6 G. Ilie, 1 J.Jolie, 1 A. Khaplanov, 7 I. Kojouharov, 2 M. Kmiecik, 8 R. Kumar, 14 N. Kurz, 2 S. Lalkovski, 11,12 A. Maj, 8 S. Mandal, 15 V. Modamio, 3 F. Montes, 2 S. Myalski, 8 W. Prokopowicz, 2 P.Reiter, 1 H. Schaffner, 2 G. Simpson, 16 D.Sohler, 13 S.J. Steer, 5 S. Tashenov, 2 J. Walker, 3 H.J. Wollersheim 2 & O. Wieland 10 127 Cd was produced both in fragmentation of 136 Xe beam @ 750 MeV/u and in fission of 238 U beam @ 650 MeV/u .The intensities of the beams were ~ 7.4 X 10 8 ions/s and ~ 2.7 X 10 8 ions/s respectively 9 Be targets of thickness 1g/cm 2 and 4g/cm 2 were used for fission and fragmentation of 238 U and 136 Xe beams respectively The observed neutron single particle evolution helps in determining the monopole interaction used in SM calculation . The comparison of theoretical predictions and experimental results provides a means for understanding the structure of neutron rich isotopes below 132 Sn and possible on-set of collectivity. 1 Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany. 2 Gesellschaft für Schwerionenforschung (GSI), D-64291 Darmstadt, Germany 3 Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049 Madrid, Spain. 4 IEP, Warsaw University, PL-00681 Warsaw, Poland. 5 Department of Physics, University of Surrey, Guildford, GU2 7XH, UK. 6 Department of Physics, Lund University, S-22100 Lund, Sweden. 7 KTH Stockholm, S-10691 Stockholm, Sweden.. 8 The Henryk Niewodniczański Institute of Nuclear Physics, PL-31342 Kraków, Poland. 9 Universidad de Santiago de Compostela, E-175706 Santiago de Compostela, Spain. 10 INFN, Universitádegli Studi di Milano and INFN Seizone di Milano,I-20133 Milano, Italy. 11 School of Engineering, University of Brighton, Brighton, BN2 4GJ, UK. 12 Faculty of Physics, University of Sofia, BG-1164 Sofia, Bulgaria. 13 Institute National Polytechnique de Grenoble , F – 98026 Grenoble Cedex , France 14 Inter University Accelerator Centre, New Delhi, India. 15 University of Delhi, New Delhi, India. 16 Institut Laue-Langevin, F-38042 Grenoble, France. FRAGMENT SEPARATOR Z Measurement Energy loss in two MUlti Sampling Ionisation Chambers at S4 A/Q Measurement Time of flight measurement between scintillators Sc21 at S2 and Sc42 at S4 Bρ-ΔE-Bρ method (Achromatic Mode) SM The decay of yrast (19/2 + ) isomer was observed in 127 Cd. Based on the measured half-life T 1/2 = 17.5(3)µs , primary decay transitions were assigned to be an E3 of 849 keV and M2/E3 of 739 keV. TOF : βγ DIPOLE : 127 Identification plot Energy and lifetime information from the gamma array Gamma coincidence spectra gated on 739 keV Time distribution obtained by summing the gates at 712 keV, 739 keV, 821 keV, and 849 keV on the energy vs time matrix A maximum likelihood fit gives a half life of T 1/2 = 17.5(3) µs

description

ISOMER SPECTROSCOPY OF 127 Cd. F.Naqvi, 1,2 M. Górska, 2 L. Cáceres, 2,3 A.Jungclaus, 3 M. Pfützner, 4 H. Grawe, 2 S. Pietri, 2 P. H Regan, 5 - PowerPoint PPT Presentation

Transcript of ISOMER SPECTROSCOPY OF 127 Cd

Page 1: ISOMER SPECTROSCOPY OF  127 Cd

RESULTS:Singles Gamma Spectra

Five gamma energy transitions were observed with energies739 keV, 822 keV , 712 keV 849 keV and 111 keV

γ –γ Coincidence Spectra

Life time measurement

Shell Model calculation predicted the existence of (19/2+) isomer of a similar half life in 127Cd . A calculation using the E3 strength of the neighbouring 129Sn isotone gives similar life time supporting the spin assignment .

The energy of 13/2- state ,obtained in Shell Model calculation is too high compared to the experiment value . Hence, a modification of the monopole interaction used in the calculation is required.

EXPERIMENTAL TECHNIQUE:

In achromatic mode the fragments with same A/Q ratio are focused at the same position on the final focal plane

Life Time Analysis

100

1000

10000

0 10000 20000 30000 40000 50000

Time [ns]

Cou

nts

/ 250

0[n

s]

T1/2 = 17.5(3)µs

RISING gamma array

15 Euroball cluster detectors with 7 crystals eachPhotopeak efficiency ~ 15 % at 1 MeV

EXP

48Cd79 is a neutron rich nucleus which has 3 neutrons and 2 protons less than the doubly magic 132 Sn . The latter nucleus is a benchmark for nuclear structure investigations.

Systematics of the Cd isotope chain shows evolution of neutron single particle energy levels.

F.Naqvi,1,2 M. Górska,2 L. Cáceres,2,3 A.Jungclaus,3 M. Pfützner,4 H. Grawe,2 S. Pietri,2 P. H Regan,5

D. Rudolph,6 Z. Podolyák,5 K. Andgren,7 T. Beck,2 B. Bednarczyk,2,8 J. Benlliure,9 G. Benzoni,10 A.M. Bruce,11 E. Casarejos,9 B. Cederwall,7 F. Crespi,10 P. Detistov,12 Zs. Dombrádi,13 P. Doornenbal,2 H. Geissel,2 J. Gerl,2 J. Grębosz,2,8 B. Hadinia,7 M. Hellström,6 R. Hoischen,2,6 G. Ilie,1 J.Jolie,1 A.

Khaplanov,7 I. Kojouharov,2 M. Kmiecik,8 R. Kumar,14 N. Kurz,2 S. Lalkovski,11,12 A. Maj,8 S. Mandal,15 V. Modamio,3 F. Montes,2 S. Myalski,8 W. Prokopowicz,2 P.Reiter,1 H. Schaffner,2 G. Simpson,16 D.Sohler,13 S.J. Steer,5 S. Tashenov,2 J. Walker,3 H.J. Wollersheim2 & O. Wieland10

127 Cd was produced both in fragmentation of 136 Xe beam @ 750 MeV/u and in fission of 238U beam @ 650 MeV/u .The intensities of the beams were ~ 7.4 X 108 ions/s and ~ 2.7 X 108 ions/s respectively

9Be targets of thickness 1g/cm2 and 4g/cm2 were used for fission and fragmentation of 238U and 136Xe beams respectively

The observed neutron single particle evolution helps in determining the monopole interaction used in SM calculation .

The comparison of theoretical predictions and experimental results provides a means for understanding the structure of neutron rich isotopes below 132Sn and possible on-set of collectivity.

1Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany. 2Gesellschaft für Schwerionenforschung (GSI), D-64291 Darmstadt, Germany

3Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.4IEP, Warsaw University, PL-00681 Warsaw, Poland.

5Department of Physics, University of Surrey, Guildford, GU2 7XH, UK.6Department of Physics, Lund University, S-22100 Lund, Sweden.

7KTH Stockholm, S-10691 Stockholm, Sweden.. 8The Henryk Niewodniczański Institute of Nuclear Physics, PL-31342 Kraków, Poland.

9Universidad de Santiago de Compostela, E-175706 Santiago de Compostela, Spain. 10INFN, Universitádegli Studi di Milano and INFN Seizone di Milano,I-20133 Milano, Italy.

11School of Engineering, University of Brighton, Brighton, BN2 4GJ, UK.

12Faculty of Physics, University of Sofia, BG-1164 Sofia, Bulgaria.13Institute National Polytechnique de Grenoble , F – 98026 Grenoble Cedex , France

14Inter University Accelerator Centre, New Delhi, India. 15University of Delhi, New Delhi, India.

16Institut Laue-Langevin, F-38042 Grenoble, France.

FRAGMENT SEPARATOR

Z MeasurementEnergy loss in two MUlti Sampling Ionisation Chambers at S4

A/Q Measurement Time of flight measurement between scintillators Sc21 at S2 and Sc42 at S4

Bρ-ΔE-Bρ method (Achromatic Mode)

SM

The decay of yrast (19/2+) isomer was observed in 127Cd.

Based on the measured half-life T1/2 = 17.5(3)µs , primary decay transitions were assigned to be an E3 of 849 keV and M2/E3 of 739 keV.

TOF : βγ

DIPOLE : Bρ

127

Identification plot

Energy and lifetime information from the gamma array

Gamma coincidence spectra gated on 739 keV

Time distribution obtained by summing the gates at 712 keV, 739 keV, 821 keV, and 849 keV on the energy vs time matrix A maximum likelihood fit gives a half life of T1/2 = 17.5(3) µs