observations, and preliminary results with a novel low energy tof …weick/frs-user2011/... ·...

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