Moller Polarimeter

General information

This article will cover all things Hall-C Moller. Currently, this includes all of the Qweak information. Information for past experiments can be found in the experiments section. This page is currently under construction, so please come back soon for more, or update me.

Documentation and references

The following are useful references:

• Sign of the beam polarization
• Moller NIM Article (NIM A Server or arXiv)
• Matthias Loppacher's thesis (pdf)
• Sarah Phillips' note on g0 Forward Angle Polarimetry (pdf)

The following is a plot showing a good tune of the apparatus. It was taken Jan 30, 2011 from run 700, with conditions: hallc:p is 1159 MeV, with a 1um target.

The preferred Moller set-up for Qweak Run II are as follows:

Quad 1: 93.5 A
Quad 3: 126 A
Col #		Position (cm)
1		-1.60
2		-1.60
3		-4.10
4		-4.10
5		Out of beam
6		-3.40
7		-3.20

For Qweak Run I, the set-up was:

Quad 1: 93 A
Quad 3: 129 A
Col #		Position (cm)
1		-1.55
2		-1.55
3		-4.05
4		-4.15
5		Out of beam
6		-3.20
7		-3.20

Hardware configuration & changes

Nov 30, 2011 Increased most of the scintillator voltages during our commissioning gain matching.

	New HV	Old HV
Left	1640	1630
Right	1685	1655

NB: Up until last run in December (date tbd)we used BCM 2 with gain from Kat's Faraday cup measurements.

• (Jan 30, 2011) Increased the left and right detector high voltages, as seen below. This is a significant change in the voltages since tune-up, and is evidence of pmt radiation effects.

	New HV	Old HV
Left	1630	1480
Right	1655	1520

• We've been having trouble with large charge asymmetries after switching the IHWP. To fix this, we've been slightly altering the Pockel cell HV. Apparently the wiki didn't save the numbers when I put them in earlier, so I'll put the ones I don't have with me in tomorrow.

IHWP	IN	OUT
POS	43886	42886
NEG	40291	41291

Experiments

• Sane Experiment
  • Sane Moller How-to

• Qweak
  • Qweak Moller How-To (pdf)
  • Qweak Moller How-To (tex file)