1. Perspectives for Nuclear Spectroscopy at the UNILAC
J. Gerl, M. Gorska
GSI Darmstadt, Germany
UNILAC Workshop
GSI

2. Focus of GS: Spectroscopy employing RIBs at SIS/FRS
VEGA - RISING – PRESPEC – HISPEC/DESPEC
Nuclear Shell structure
N ≈ Z
N>>Z
Nuclear shapes
Quadrupole, Octupole, Triaxiality
Shape transitions
High K-isomers
Collective modes
N>>Z : GDR soft mode
Nuclear Symmetries
mirror-isospin, pn-pair correlation
Nuclear astrophysics
r, rp process
Relativistic Coulomb excitation, Fragmentation and Decay studies using
Rare Isotope Beams and high-resolution  Spectroscopy 15

3. Complementary Experiments at UNILAC
Nuclear Shell structure
N ≈ Z
N>>Z
Nuclear shapes
Quadrupole, Octupole, Triaxiality
Shape transitions
High K-isomers
Collective modes
N>>Z : GDR soft mode
Nuclear Symmetries
mirror-isospin, pn-pair correlation
Nuclear astrophysics
r, rp process
Multiple Coulomb excitation, Transfer, Deep inelastic reactions,
Fusion evaporation, Fission and Decay studies using
Stable Isotope Beams and high-resolution  Spectroscopy 15

4. 100Sn as example for multitude of techniques
Fusion symmetric
reaction
EXOGAM, EUROBALL,
GASP..
+ Ancillaries
- in-beam
MSEP at GSI
- β decay
- spin-gap isomers
Argonne/OakRidge
- α-decay
Fragmentation
GSI, RIBF,
NSCL, GANIL
- Coulex
-Transfer
- Isomers 15

5. Spin gap and seniority isomers below N = Z = 50
with RISING and
GSI - ISOL
proton – neutron
hole-hole interaction
in p n g9/2-n
core excitation
in large-scale SM
in p n g9/2-1 (d5/2 ,g7/2)1
100Sn is doubly magic so there is plenty of seniority and spin gap isomers at intermediate and high spins. We have to be carefull not to miss any yrast isomer (which happened in the past) therefore fusion evaporation is the best choice.
Fusion evaporation reactions best to avoid missing isomers! 15

6. NUSTAR instrumentation for spectroscopy
HISPEC
-LYCCA heavy ion calorimeter with ToF capability in operation
-AGATA gamma spectrometer in operation
-Hyde light particle array prototype
-NEDA Neutron detector array prototype
-EDAQ dedicated electronics and DAQ based on several branches
DESPEC
-AIDA active implantation device prototype
-MONSTER neutron ToF array under construction
-BELEN neutron detecion array in operation
-DTAS Decay Total Absorption Spectrometer in operation
-DEGAS Ge Array gamma spectrometer in development
-FATIMA Fast timing array in operation
-EDAQ dedicated electronics and DAQ based on several branches 15

7. DEGAS Detector Realization
TDR approved in
HPGe Crystal
Crystal capsule
Backcatcher
Bottom Deck
(BC electronics,
later Ge-DAQ)
Middle deck
(Ge-PA + HV)
Top Deck
(Support electronics,
power supply and µPC)
Connectors
Holding bars
Design work finished
Ge Array with 28 Triples
scrutinized by IFIN-HH
Pre-series construction started
Funding: Phase I 100% secured
Phase II 80% secured 15

8. Example: Isomerism in 94Pd
Reaction: 40Ca (~170 MeV) + 58Ni (>2 mg/cm2) -> 2p2n + 94Pd
DEGAS+NEDA+FATIMA
Time difference between two coincident γ rays detected in FATIMA γ ray(s) in DEGAS and a 2n gate in NEDA
Total cross section ~1b Interesting exit channel ~1μb
Particle selection
We are not aware of any prompt evaluation of any prompt evaluation of excited states in 94Pd W
The 15 8

9. Typical fusion evaporation cross section distributions
Narrow resonances
eg. 104Sn: Ebeam = MeV/u
50Cr + 58Ni -> 108Te*
Tunable beam energy required 15

10. Prompt and delayed spectroscopy in 98Cd
58Ni + 46Ti → 104Sn* → 98Cd + α2n
At the catcher:
εp~55%
εα~10%
εn~25%
εγ~3.5% 8+
2428 6+
2281 4+
2083 2+
1395 0+
M.Górska et al., Phys. Rev. Lett. 79 (1997) 2415
R. Grzywacz et al., ENAM 98 AIP CP 455 (1998) 430
Similar set-up needed at X7 15

11. Example: Lifetime of heavy nuclei
Evolution of collectivity in heavy nuclei
 transfer reaction
e.g. 12C(204Pb, 208Po)8Be
Ebeam = 5.9 MeV/u
M. Reese, GSI 15

12. Spin-oriented isomers probing nuclear moments
Pulsed beam – nuclear reaction on target –
TDPAD (Time Dependent Perturbed Angular Distribution) of  rays
H. Watanabe, RIKEN 15

13. Example: g-factors from isomer decays
H. Watanabe, RIKEN 15

14. Requirements for Gamma spectroscopy at UNILAC
Prompt measurements:
broad range of beam isotopes
exactly tunable beam energy (3-7 MeV/u)
long pulses (DC beam)
high duty cycle
moderate intensities
broad range of targets
Fusion evaporation, Deep inelastic, Transfer, multiple Coulex
Delayed measurements:
broad range of beam isotopes
exactly tunable beam energy (3-7 MeV/u)
short pulses possible
moderate to high duty cycle
moderate to high intensities
broad range of targets
Fusion evaporation, Deep inelastic, Fission 15

15. Gamma Spectroscopy Programme at UNILAC
Complementary to HISPEC/DESPEC runs at GSI/FRS and FAIR/Super-FRS
Requested beam time: 4-8 weeks/a
Location: X7 cave (SHIP, TASCA in collab. with SHE groups)
Instrumentation: Detectors from HISPEC/DESPEC (in the 11 months/a without RIB availability)
Attractive for the NUSTAR physics community
Substabtial addition to scientific output of nuclear spectroscopy at GSI 15