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

Layout of a fast-beam experiment at NSCL…

A1900 fragment separator

Identification and beam transport80-100MeV/nucleon100-106 pps

Reaction target100-400mg/cm2

Production targetBeam energy from cyclotrons 100-150MeV/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

S800

36Ar

28Si

θ

Ge

v/c ≈ 0.4

ϴ [

rad]

in G

RE

TIN

A

energy [keV] (laboratory frame)

(Obvious) requirements for a spectrometer:

Doppler-shift correction Spatial resolutionLorentz Boost Detection efficiency at forward angle

…and GRETINA is a perfect match

γ rays of 28Si at v/c = 0.38 inGRETINA

…but GRETINA does much more

plain singles tracked*

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

64Ge γ-γ, produced from 65Ge on 9Be at v/c=0.4

GRETINA/S800 data acquisition

GRETINADAQ + GEB S800 DAQ

NSCL DAQ framework:-Run Control-Online Analysis-(s800) event data traffic

start

/stop

start/stop

S800 data

GR

ET

INA

+S

800 data

S800

dat

a

Storage of production dataon GRETINA disk array

data sample

onlin

e data

Online a

nalysis

*Gretina Event Builder

*

GRETINA/S800 triggering/synchronization

GRETINADAQ S800 DAQ

GRETINAclock

Important note:If GRETINA runs intodeadtime, no busy signalor 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 ns600 ns

GRETINA leading edge timingThis 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 rayof 60Co source

ener

gy

ener

gy

FWHM after Doppler-shift reconstruction

Energy [kev]

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!

Absolute ‘singles’ efficiency (no addback)

Energy [keV]

Abs

olut

e ph

oto-

peak

eff

icie

ncy

[%]

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 hrs2) 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 hrs17) 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

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

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

23 Expts3360 hrs

done through February 2013

Prepared by H. Crawford, LBNL