Binary Reaction Spectroscopy from A=100-200 Paddy Regan

Dept. of Physics, University of Surrey,

Guildford, GU2 7XH, UK

e-mail: p.regan@surrey.ac.uk

Problems with neutron-rich spectroscopy ?

• Production (RIBs, fission, binary reactions).– Small cross-sections, need high efficiencies.

• Identification (N,Z)– lots of products, need clean id or ‘tags’ (e.g. isomers)

• Population in (Ex,I) plane (reaction selection)– need to know spin/excitation energy range of products

2)12( L

Modified from Introductory Nuclear Physics, Hodgson, Gadioli and Gadioli Erba, Oxford Press (2000) p509

Aim? To perform high-spin physics in stable and neutron rich nuclei. Problem: Fusion makes proton-rich nuclei.Solutions? (a)fragmentation (b) binary collisions/multi-nucleon transfer

See eg.Bock et al., Nukleonika 22 (1977) p529 Broda et al. Phys. Rev Lett. 74 (1995) p868Juutinen et al. Phys. Lett. 386B (1996) p80Wheldon et al. Phys. Lett. 425B (1998) p239 Cocks et al. J. Phys. G26 (2000) p23Krolas et al. Acta. Phys. Pol. B27 (1996) p493Asztalos et al. Phys. Rev. C60 (1999) 044307

CCMMAX

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31

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:limit Rolling

Can not use fusion-evaporation reactions to study high-spin states (and thus vibrational-rotational transitions, alignments etc.) in beta-stable and neutron-rich systems.

Use deep-inelastic reactions.

Z

N

Ebeam ~15-20% above Coulomb barrier

beam

target

(i) (ii) (iii)

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198Pt +136Xe, 850 MeV

8+ dominated by Coulex in 198Pt. High-spin isomers kill prompt DIC

100Mo + 136Xe @ 750 MeVGAMMASPHERE + CHICO

TLFs

BLFs

elastics

TLFs

BLFs

elastics

Wilczynski Plot

Isomer gating very useful in DIC experiments. Test with known case…..

Pt+Xe Mo+Xe

max

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3/13/1

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v/c graz tlf

Linear(%>Ecoul)

0

10

20

30

40

50

60

620 648 677 705 733 761 790E_beam (MeV)

blf_graz

tlf_graz

lmax/10

Kinematics and angular mom. input calcs (assumes ‘rolling mode’) for 136Xe beam on 100Mo target.

Estimate ~ 25hbar in TLFfor ~25% above Coul. barrier. For Eb(136Xe)~750 MeV, in labblf~30o and tlf~50o.

100Mo +136Xe (beam) DIC calcs.

Future plans? High spins (SD at I~25) in 99,100Mo. (cf. 136Xe beam with 208Pb and 238U (fission prob)

0

5

10

15

20

25

30

35

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45

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620 648 677 705 733 761 790

%>EcoulLtlf (roll)v/c graz (tlf)Linear (%>Ecoul)

Podolyak et al. Phys. Lett. 491B (2000) 225

New isomer in 195Os confirmed ‘in-beam’ CHICO+GAMMASPHERE

Dobon, Wheldon, Regan et al.,

beam-like fragment isomers.

Target-like fragment isomers

Identification of new isomeric state in 136Ba, N=80 isotone.

N=80 isotonic chain, 10+ isomersQ. Why does Ex(10+) increase while E(2+) decreases ?

Structure of 8+ appears to change from 134Xe -> 136Ba ?

1565 keV gate2+->0+ in 86Kr

Double gate on 143 and 298 keV in 188W.

432 keV6+ in 188W

82Se+192Os GaSp backed target data (Podolyak, Mohammadi, DeAngelis et al.)

many thanks to......• Jose Javier Valiente Dobon (Pt)+ Arata Yamamoto (Mo) Zsolt Podolyak, Saeed

Mohammadi, Chris Pearson, Scott Langdown, Karin Andgren (Surrey). Furong Xu (Bejing).

• Carl Wheldon (Surrey -> GSI) Spokesperson for 136Xe+198Pt.• CHICO + GAMMASPHERE Experiments

– Rochester (Chin-Yen Wu, Doug Cline, Adam Hayes, Hui Hua, Ray Teng et al.,) – LBNL (Augusto Macchiavelli, Paul Fallon, I-Yang Lee, Mario Cromaz)– Manchester. (John Smith, Sean Freeman, Ravi Chakrawarthy) – Daresbury (Dave Warner), – Paisley (Bob Chapman, Xiaoying Liang)

• Vibrator-Rotator (E-GOS) plots, Con Beausang, Rick Casten, Victor Zamfir, Jing-Ye Zhang.

NUSTAR’05International Conference on

NUclear STructure, Astrophysics and Reactions

The University of Surrey, Guildford, UK

5-8 January 2005

See strong lines in 84,86Kr (binary partners of 190,188W). Identify first three states in 188W. GaSp 82Se+192Os (backed target) GaSp, Podolyak, Mohammadi et al.,