Perspectives for Nuclear Spectroscopy at the UNILAC J. Gerl, M. Gorska GSI Darmstadt, Germany UNILAC Workshop GSI 22.8.2016

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

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

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

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

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

DEGAS Detector Realization TDR approved in 7.2015 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

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

Typical fusion evaporation cross section distributions Narrow resonances eg. 104Sn: Ebeam = 3.6-4.4 MeV/u 50Cr + 58Ni -> 108Te* Tunable beam energy required 15

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

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

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

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

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

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