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

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

(Find) GRETINA in S3

Gamma spectroscopy with fast beam S Ar 28 Si θ Ge v/c ≈ 0.4 [rad] in GRETINA 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 γ rays of 28 Si at v/c = 0.38 in GRETINA

…but GRETINA does much more plain singlestracked * 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. * Tracked and provided by I-Yang Lee 64 Ge γ-γ, produced from 65 Ge on 9 Be at v/c=0.4

GRETINA/S800 data acquisition GRETINA DAQ + GEB S800 DAQ NSCL DAQ framework: -Run Control -Online Analysis -(s800) event data traffic start/stop S800 data GRETINA + S800 data Storage of production data on GRETINA disk array data sample online data Online analysis * G retina E vent B uilder *

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

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

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

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

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

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

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 hrs 19) Anomalous quadrupole collectivity in light Sn isotopes, 213 hrs 20) Proton Inelastic Scattering in 70, 72Ni, 90 hrs 21) Inelastic Excitations Beyond 48Ca, 153 hrs 22) 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

GRETINA Experiments at NSCL Nuclear Shell Evolution N=Z Mirror Spectroscopy Structure in 221,223 Rn Ca neutron knock-out Neutron-rich Ti Odd neutron-rich Ni 34 Si 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 58 Zn Measurement of the 56 Ni(d,n) 57 Cu transfer reaction Collective Nuclear Structure Transition matrix elements in 70,72 Ni 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 12 Be Ni excited-state lifetimes Inelastic excitations beyond 48 Ca Triple configuration coexistence in 44 S GT strength distributions in 45 Sc and 46 Ti Search for isovector giant monopole resonance 23 Expts 3360 hrs done through February 2013 Prepared by H. Crawford, LBNL