R.J. Feuerbach Report: Oct 18, 2006

Neutron detector calibration

  1. Neutron timing calibration completed, with intra-detector (plane-to-plane and intraplane bar-to-bar) time difference distributions with sigma's less than 400ps, which equates to a sub-300ps bar resolution.
  2. Comparison of BB time to Neutron Detector for ELASTIC Hydrogen run 4427. After pathlength (BB and ND) and RF corrections, a sigma of 390ps was achieved (somewhat disappointing).

Cooking progress



Out of ~650 files, all but 124 are finished and generally look good. Some runs with Helicity warning, but more than 90% are fine.

Momentum distributions

The neutron/proton candidate's beta and momentum was calculated from the time-of-flight of the particle observed in the neutron detector. Here is the Inverse-Beta distribution for all candidate clusters in the neutron detector. Only clusters with an Inverse-Beta between 1 and 1.8 (nucleon momentum above 630 MeV/c) were used later to generate the momentum distributions. The shaded region in 0.0<1/beta<0.8 was used to generate accidental background distributions, shown in light-green below.

Protons

Looking at parallel and perpendicular momentum distributions. Run 4470 is a He3 run, run 4582 is a Carbon run, run 4427 is a hydrogen run.
  1. He3 Proton Pparallel-q He3 Proton Pperp
  2. Carbon Proton Pperp
  3. H Proton Pperp
The peak in Pperp for the Carbon is around 100 MeV/c, right where the literature shows the 1P shell populates (thanks Bogdan).

Neutrons

  1. He3 Neutron Pparallel - q, He3 Neutron Pperp
  2. Carbon Neutron Pperp
  3. H Neutron (??) Pperp
Background under the neutron at large negative "Pparallel-q" is the flat (in time) accidental background.

A look at the Pparallel-q 1-D projections, with cuts on W<1.16 GeV and Pperp<110 MeV/c shows:

  1. He3 run 4470 (green is accidental coincidences)
  2. H run 4427 (green is accidental coincidences)
  3. Carbon run 4582 (green is accidental coincidences)

Cleaning up of Clusters in ND

Some clusters are still broken into multiple parts in the neutron detector. This has to be refined.