From naranjo Mon Nov  8 23:10:55 2004
Date: Mon, 8 Nov 2004 23:10:55 +0000
To: michael.loughlin@ukaea.org.uk, APX077@coventry.ac.uk,
        nigel.hawkes@npl.co.uk, colin.murray.01@bbc.co.uk
Cc: puherman@ritva.physics.ucla.edu, camara@physics.ucla.edu,
        shopkins@scs.uiuc.edu
Subject: UCLA PSD waveforms
Reply-To: Brian Naranjo <naranjo@physics.ucla.edu>

Hi All,

I'm glad to hear that the filming went well.  To further clarify the
pulse shape discrimination, I've attached some examples of typical
neutron detector waveforms.

PSD Test Waveforms
==================
Given a proton candidate 'test[[i]]' having 'energy' and PSD value 'ratio',
I calculate
  chi^2 = Sum[ (test[[i]]-typical[[i, energy, ratio]) /
     error[[i, energy, ratio]])^2, {i, 1, 500} ] / 499.
Proton candidates having chi^2 greater than 1.5 are rejected.

Typical waveforms and their associated errors are determined by AmBe source
calibration.  For example, an ~800 keV proton is shown on page 1.  The PMTs
have a slight ion feedback tail pulse at 450-500 ns and a much stronger
tail pulse at around 1 us, not included in the chi^2 test.


PSD 01 - Background Cosmics - RejectedWaveformAnalysis
======================================================
These are typical waveforms that reside in the proton region but
fail the chi^2 test.  These 12 events took 1400 seconds to collect,
so double pulsing is a relatively rare occurrence.  One fascinating
event was (acq=433,seg=875), where a double cosmic pulse registered
in both channels.  In BBC 03, there was one rejected double gamma.


PSD 01 - Background Cosmics - WaveformAnalysis
==============================================
typical electron recoil waveforms


PF 12 - 2.45 MeV Neutrons - AcceptedWaveformAnalysis
====================================================
Shown are scintillations caused by 2.45 MeV neutrons coming
from my homemade electrostatic DD neutron generator.  Note
that proton_chi clusters around 1.0, as expected.  The pulse
height spectrum agrees with my calculated Monte Carlo spectrum
(see 'UCLA Neutron Detector Notes').

Brian
