observations, and preliminary results with a novel low energy tof …weick/frs-user2011/... ·...
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Observations, and preliminary Observations, and preliminary results with a novel Low Energy results with a novel Low Energy
ToF Neutron Array (LENA) in ToF Neutron Array (LENA) in the S408 experimentthe S408 experiment
A. Krasznahorkay, ATOMKI, DebrecenA. Krasznahorkay, ATOMKI, Debrecenfor the R3B and EXL collaborationsfor the R3B and EXL collaborations
( )pnSDRSDR rZrNSS ⟩⟨−⟩⟨=− +− 22
29π
2/122/12pn rrR ><−>=<∆
2/12
2/12exp
2
)()1(2/122/12
p
p
rN
rZNBpn rr
><
><−−−=><−>< ασ
Sum rule for the GDR strengthNeutron‐skin thickness
−+= SSB /
Bohr, Mottelsson Nuclear Structure (1969) Vol. 2
A. Krasznahorkay et al., Phys. Rev. Lett. 82 (1999) 3216.
The The 124124Sn(p,n) reaction in inverse Sn(p,n) reaction in inverse kinematicskinematics
Relativistic calculationof inverse kinematics 132Sn
EEbeambeam=600 MeV=600 MeV··AA124124SnSnEExx(GDR)=18(GDR)=18--24 MeV24 MeVΘΘcmcm=3=3°°--44°° (L=1)(L=1)
65°<Θlab<75°
Θcm
2.5°
2.0°
3.0°
3.5°
3530 25 20 15Ex:
1.0°
GroundGround--state state γγ--decay of the decay of the GDRGDR
44
Recent publ: Utsunomiya et al., PRC 84 (2011) 055805
Schematic layout of the setupSchematic layout of the setup
LENA neutron detectorsLENA neutron detectors
3x5 Det.
Efficiency for neutronsEfficiency for neutrons
Installation of the LENA detectorInstallation of the LENA detector
The role of the background The role of the background coming from the beam linecoming from the beam line
ToF spectra with different cutsToF spectra with different cuts
Energy distribution of the Energy distribution of the neutronsneutrons
QuasiQuasi--free charge exchange free charge exchange processprocess or GDR (both)?or GDR (both)?
Detection of the Detection of the γγ--raysrays
Installation of the LaBrInstallation of the LaBr33detectorsdetectors
Thank you for your attention !Thank you for your attention !
HHigh energy spectraigh energy spectrameasured in Debrecenmeasured in Debrecen
Ga-66 Na-23
Li-7
Integral nonlinearityIntegral nonlinearity
Energy resolutionEnergy resolution
Relative efficiency of the Relative efficiency of the detectordetector
Eff. (%)
E (keV)
Excitation of the GDR in the Excitation of the GDR in the 124124Sn beamSn beam
Identification of the particlesIdentification of the particles
Using the FRS for particle Using the FRS for particle identificationidentification
Maierbeck et al.,Physics Letters B 675 (2009) 22–27
THANK YOUTHANK YOU