Identification of Neutral Particles with PANDORA Detector and Pulse-Shape Discrimination Method

Spin-isospin excitations provide a unique opportunity to
study the spin correlations in nuclei.
 Recently the technique of inverse kinematics enables the (p,n)
reactions on exotic nuclei.
 Low energy neutrons are measured by neutron detectors with the
time-of-flight (TOF) method.
 In this method, we cannot distinguish the neutrons from the
random gamma background, and thus the background events would
limit the beam intensity due to the lifetime of data acquisition.
 To solve this problem, a plastic scintillator (PANDORA), 
which is sensitive to the differences
between neutrons and gamma rays, has been introduced.
 The performance of the neutron-gamma discrimination
was known for a few hundred keV to a few MeV neutrons.
 We have taken new data for 4-60 MeV neutrons produced
by the deuteron-breakup (d,n) reactions using a 55 MeV
deuteron beam at RCNP, Osaka University.
 The CAEN's pulse shape discrimination (PSD) firmware has
been used to perform the neutron-gamma discrimination
in real-time.
 The neutron-gamma discrimination has been succeeded
in the preset energy region, showing the usefulness
of the PANDORA detector in the wide energy region.
 We will present these new data and discuss about
the validity of the real-time discrimination with PSD.