Run 12 configuration (p-Carbon)

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Last modified by Schmidke on 9-05-2012

Run 11 configuration Run 12 configuration Run 13 configuration

An overview: DAQ configuration, detectors & target assignments, Am/Gd source locations

In the transition from 100->250 GeV beams, most of the targets were replaced, and some detector changes were made; here is an overview

Polarimeter B2D is somewhat 'experimental', with two longitunally segmented detectors, 4 Hamamatsu and several test targets


The readout has been returned to independent systems for the Blue and Yellow polarimeters. This will hopefully improve stability. Also setup and adjustment of e.g. timing parameters should be simpler and faster.


Most of the detectors are reused from Run11, with minimal rearrangement. The only changes were:

  • 2 BNL 'short pin' detectors moved from B2D to Y1D
  • 2 Hamamatsu detectors moved from Y1D to B2D; one drew high current, replaced with a spare Hamamatsu
  • 2 new BNL 1 mm detectors installed in B2D; 2 old BNL 'short pin' removed

Summary of detectors in each polarimeter, with details (wafer, chip):

  • B1U: 6 BNL 'long pin' details
  • B2D: 4 Hamamatsu (ports 2-5); 2 BNL 1mm (45-deg. ports 1,6), rotated for logintudinal segmentation details
  • Y1D: 4 BNL 'long pin' (ports 1,3,4,6); 2 BNL 'short pin' (90-deg. ports 2,5) details
  • Y2U: 6 BNL 'long pin' details

In the transition from 100->250 GeV beams the following detector changes were made:

  • Y1D detectors 1,6 (top 45-deg. ports) were moved ~1 cm farther from the beam with spacers under the flange
  • Y1D detectors 3,4 (bottom 45-deg. ports) were replaced with BNL 'short pin' detectors

This was an effort to reduce noise by placing the detectors farther from the mesh screen in the hole to the scattering chamber


Most of the targets are from the standard fabrication technique, thinnest and narrowest nominal size: 25 nm thick x 7-10 wide x 25 mm long

Special targets (nominal dimensions except as noted) and locations are:

  • 4 highly twisted targets (B1U H3,H6; B2D V3,V6)
  • 3 short targets 20 mm long (B1U H5; B2D V5; Y1D H6)
  • 1 wide target 50-75 wide (B2D H4)
  • 1 very wide target 5 mm wide, fixed angle w.r.t. beam, detectors (B2D H6)

Their purposes are:

  • High twist targets may average out instabilities due to rotation about the long axis. The high twist H targets in B1U should be run with the V ones in B2D to allow check of stability from ratio B1U/B2D
  • Short targets are test of alignment etc. with narrower gap frame. In future may allow 8 targets per frame
  • Wide target is for 'rate tests'
  • Very wide target has fixed orientation with respect to beam and detectors, therefore fixed energy loss

A grid of special target locations (T=twisted, S=short, W=wide, V=very wide) and detailed target info for each ladder:

Target Ribbons
target 1 2 3 4 5 6
B1U-V details
B1U-H T S T details
B2D-V T Sa T details
B2D-H W V details
Y1D-V details
Y1D-H S details
Y2U-V details
Y2U-H details

The table shows installed configuration; susequent info on target status indicated by superscripts:

a) 14.12.11 visual observation showed target is gone

Many of the targets were lost in the 100 GeV running; in the transition to 255 GeV 42 of the 48 targets were replaced. No short, wide, or very wide targets were reinstalled. Two targets made by the TRIUMF laser ablation technique were installed.

A grid for 250 Gev running of special target locations (T=twisted, L=laser ablated) and detailed target info for each ladder:

Target Ribbons
target 1 2 3 4 5 6
B1U-V details
B1U-H T T details
B2D-V details
B2D-H L details
Y1D-V details
Y1D-H T details
Y2U-V T details
Y2U-H L details

Regrettably, the targets again disappeared at a high rate during the 255 GeV running. They were all replaced on April 11 for the last week of the run; details not yet available.

Alpha Sources

As in previous years there are Am sources at all 90-deg. ports. Gd sources have also been installed at the 90-deg. ports in B2D and Y2U

Last modified by Schmidke on 9-05-2012