GRETINA experiments with fast beams at NSCL

1. GRETINA experiments with fast beams at NSCL Dirk Weisshaar, NSCL @ • GRETINA and fast-beam experiments • Some details on implementation at NSCL • Performance results • Overview on GRETINA experiments at NSCL

2. Layout of a fast-beam experiment at NSCL… …involving the S800 spectrograph Reaction target 100-400mg/cm2 Identification and beam transport 80-100MeV/nucleon 100-106 pps Reaction product identificationS800 spectrograph A1900 fragment separator Production target Beam energy from cyclotrons 100-150MeV/nucleon Length ~80m (260 ft)(linear distance)

3. (Find) GRETINA in S3

4. Gamma spectroscopy with fast beam Ge γ rays of 28Si at v/c = 0.38 in GRETINA 36Ar θ ϴ [rad] in GRETINA v/c ≈ 0.4 S800 28Si energy [keV] (laboratory frame) • (Obvious) requirements for a spectrometer: • Doppler-shift correction •  Spatial resolution • Lorentz Boost •  Detection efficiency at forward angle • …and GRETINA is a perfect match

5. …but GRETINA does much more 64Ge γ-γ, produced from 65Ge on 9Be at v/c=0.4 plain singles tracked* * Tracked and provided by I-Yang Lee Reduction of Compton background by tracking allows – for the first time – gamma spectroscopy with fast beams with spectral quality comparable to arrays with anti-Compton shield, i.e. GammaSphere.

6. GRETINA/S800 data acquisition • NSCL DAQ framework: • Run Control • Online Analysis • (s800) event data traffic start/stop start/stop S800 data S800 data online data GRETINA DAQ + GEB * S800 DAQ data sample GRETINA + S800 data Online analysis Storage of production data on GRETINA disk array *Gretina Event Builder

7. GRETINA/S800 triggering/synchronization Downscaled, 12.5MHz GRETINA clock Gamma-ray trigger S800 focal plane trigger ~250ns latency GRETINA DAQ S800 Trigger Logic S800-GRETINA Coincidence window: 600ns Trigger signal issued ~900ns after particle detection in S800 S800 DAQ Important note: If GRETINA runs into deadtime, no busy signalor the like is provided. Trigger live out

8. GRETINA timing GRETINA leading edge timing This timing quality is available asprompt signal (~200 ns latency) fora trigger logic. GRETINA ‘t0’ timing: This timing quality is available after decomposition, i.e. in thedata analysis. Coincidence with 1.3 MeV γ ray of 60Co source energy energy 600 ns 600 ns

9. FWHM after Doppler-shift reconstruction 28Si from 36Aron 47 mg/cm2 Bev/c = 0.38 full GRETINA Measured FWHM of 1.00%meets expectation based on σ=2mm spatial resolution! Energy [kev]

10. Absolute ‘singles’ efficiency (no addback) Absolute photo-peak efficiency [%] Energy [keV]

11. The helium story…. While the tracking modules run stable since the NSCL commissioning run, we saw this: LBL/BGS Jun-Sep T-plot prepared by J. M. Allmond ORNL

12. PAC-approved experiments with GRETINA Experiments done since summer 2012: 1) Commissioning of GRETINA + S800 spectrograph at NSCL, 98 hrs 2) Important 58Zn excitation energies for rp-process, 135 hrs 3) Gamma and gamma-gamma spectroscopy of mirror nuclei, 197 hrs 4) Single-particle structure of neutron-rich Si isotopes, 187 hrs 5) Is 34Si a "Bubble" Nucleus?, 78 hrs 6) Direct lifetime measurements of excited states in 71-74Ni, 157 hrs 7) Collectivity at the N=Z line and a novel plunger method, 139 hrs 8) Single-particle structure of neutron-rich N=40 nuclei, 129 hrs 9) Neutron knockout in the Neutron-Rich Ca Isotopes, 175 hrs 10)Measurement of Gamow-Teller strength distributions via the (t,3He+gamma) reaction on 45Sc and 46Ti, 201 hrs 11) Gamma-ray spectroscopy of neutron-rich Ti isotopes, 194 hrs 12) Single-Particle Strength in the odd, neutron-rich Ni isotopes, 107 hrs 13) A precise measurement of the B(E2:2->0) in 12Be, 87 hrs 14) Exploration of 221, 223Rn in-beam gamma-ray spectroscopy, 69hrs Just being done: 15) Coexistence in exotic C isotopes, 169 hrs

13. PAC-approved experiments with GRETINA Experiments to be done until July 2013: 16) Triple configuration coexistence in 44S, 115 hrs 17) Normal and intruder configurations in the Island of Inversion, 174 hrs 18) Angle integrated measurement of the 56Ni(d, n)57Cu transfer reaction, 99 hrs19) Anomalous quadrupole collectivity in light Sn isotopes, 213 hrs20) Proton Inelastic Scattering in 70, 72Ni, 90 hrs21) Inelastic Excitations Beyond 48Ca, 153 hrs22) Search for isovector giant monopole resonance, 199 hrs 23) Gamma-gamma spectroscopy of neutron-rich Mg isotopes , 195 hrs Total 3360 hrs, 2100 hrs of experiments done so far

14. GRETINA Experiments at NSCL • Nuclear Shell Evolution • N=Z Mirror Spectroscopy  • Structure in 221,223Rn  • 50-52Ca neutron knock-out  • Neutron-rich Ti  • Odd neutron-rich Ni  • 34Si Bubble nucleus?  • Neutron-rich Si  • GRETINA commissioning  • Neutron-rich N=40 nuclei  • Normal and intruder configurations in the Island of Inversion • Nuclear Astrophysics • Excitation energies in 58Zn  • Measurement of the 56Ni(d,n)57Cu transfer reaction 23 Expts 3360 hrs • Collective Nuclear Structure • Transition matrix elements in 70,72Ni • Quadrupole collectivity in light Sn • γ-γ spectroscopy in neutron-rich Mg • Neutron-rich C lifetime measurement  • Collectivity at N=Z via RDM lifetime measurements  • B(E2:2→0) in 12Be  • 71-74Ni excited-state lifetimes  • Inelastic excitations beyond 48Ca Triple configuration • coexistence in 44S • GT strength distributions in 45Sc and 46Ti  • Search for isovector giant monopole resonance  done through February 2013 Prepared by H. Crawford, LBNL