PHYSICS/MCC EXPERIMENT PLANNER
Experiment Title: Q-weak
Experiment #
Hall
E08-016
C
Start/Finish Dates
Start: 5/25/10
Total Beam Hours
Finish: 5/13/12
Experiment Contact Person: Roger Carlini
Phone: 757-269-7123
Pager:
E-mail: carlini@jlab.org
Office: 12_1/C114
Physics Liaison: Dave Gaskell
Phone: 757-269-6092
Pager:
E-mail: gaskelld@jlab.org
Office: 12_1/C128
Accelerator Representative: Jay Benesch
Phone: 757-269-6505
Pager:
E-mail: benesch@jlab.org
Office: 53A_1/4
Operations Representative: Michael McCaughan
Phone: 757-269-5572
Pager: 757-343-7123
E-mail: michaelm@jlab.org
Office: 53A_1/1
Standard Meeting Times: Mondays, 3 p.m.
Special Meetings/Presentations: HC RC meetings
Meeting Location: Cebaf Center Room A 110
RC meetings daily, 3:30 pm in Counting house (2f)
Brief Description of Experiment (as relevant to Operations): Qweak is a precision measurement of the proton's weak
charge at very low Q2 using parity violating electron scattering off of the proton. (Q PW = 1 - 4sin2Θw) A measurement of the
parity violating asymmetry in elastic ep scattering at Q 2=0.03 (GeV/c)2 employing 180 μA of 85% polarized beam on a 35
cm liquid Hydrogen target will determine the proton's weak charge with approximately 4% combined statistical and
systematic errors. A deviation from the weak mixing angle as currently theoretically predicted is an indication of new
physics and will allow for an extension of the standard model.
Additional information/training:
http://opsntsrv.acc.jlab.org/ops_docs/online_document_files/MCC_online_files/Hall_C_Qweak_Experiment_training_Green_3-17-10.pdf
http://opsntsrv.acc.jlab.org/ops_docs/online_document_files/MCC_online_files/HallC_QWeak_experiment_overview_Gaskell_5-26-10.pdf
Applicable Reading Material: http://www.jlab.org/exp_prog/proposals/08/PR-08-016.pdf
http://www.jlab.org/accel/ops/ops_liaison/Hall_C/qweak.html
Beam Requirements:
(1-pass)
Standard Energy (pass)
Nonstandard Energy (specify)
Current(s) @ Given Energy
# of Hours at Each Energy/Current
Polarization (%)
∆E/E
Beam Energy Stability
Beam Size (horizontal)
Beam Size (vertical)
Beam Size Stability
Target Types
(2pass)
(3-pass)
(4-pass)
(5-pass)
1.165 GeV
+/- 5 MeV
180 uA
2544
100%
<.1%
<∆E/E> < 10-9
<200 um
<200 um
+/- .5 mm
See below
Special Concerns: High Radiation areas at Target, Region 3, and near dump. Orbit/Energy locks on. Small aperture
through Tungsten (W) plug in scattering chamber. Do not use teleprobes in confines of QTOR due to electrical hazard.
Special MPS or PSS Issues: 16” Gate valve at 3H09 closed for accesses.
Beam Property
Requested Currents
Polarization, Longitudinal (%)
Polarization, Transverse (%)
Energy Spread (∆E/E)
Aspect Ratio
Orbit Stability
Halo Rates
Charge Asymmetry width
Beam Angle
Helicity Reversal rate
Nominal
160 uA
P > .85 Longitudinal
Requested
100 pA – 180 uA
P > .85 Longitudinal
<Py> = 0 (max excursions < 4% )
<Py> = 0 (max excursions < 4% )
-4
< 10
< 200 um x 200 um
+/- .1 mm
Normalized:
Halo 3: < 20 Halo 4 < 33
< 400
<10^-3
< 200 um x 200 um
+ - .5 mm
Parity Quality (<10-6 2mm from
beam)
< 400
0 = 60 rad
<> < 30 nrad
1 ms pseudo random quad pattern with ~ 80μs settling time & several days at other rates
Trip Rate
<10/hr.
Experiment Targets (#/nucleus)
I (limit) 15 – Al 2%
0 – LH2 (35cm cell)
16 – Al Key
1 – 2% Al
17 – Al hole – 6x6 square – upstream
2 – 8% Al
18 – Ruby Viewer
3 – 4% Al
19 – Al Optics (135)
4 – .5% C
20 – Al Optics (3)
5 – Al hole – 2x2 square – downstream
21 – Al Optics (15)
6 – 2% Be
22 – Al Optics (1235)
7 – ½” hole (Halo) target
23 – Al Optics (12345)
8 – Al hole – 2x2 square – upstream
24 – Al Optics (1345)
9 – 3.3% (or 4%) Carbon
10 – Pure Al
Other: Insertable Al flag target
11 – Empty Target Position
LH2 (35cm cell), cell empty/warm
12 – BeO
13 – Al 1%
Moeller target foils
14 – Al 4%
Info on page 10 of http://www.jlab.org/~smithg/target/Qweak/Qweak%20Tgt%20Training.pdf
I (limit)