He3 / H3 e,e'p experiment E12-14-011

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The SRC Tritium Experiment (E12-14-011) is an (e,e'p) experiment in Hall A, comparing the momentum distribution of protons in tritium and helium-3. These nuclei have a large proton-neutron asymmetry, but are also isospin-mirror nuclei, meaning that the proton distribution in tritium can tell us about the neutron distribution in helium-3.

Publications and results

  • Comparing proton momentum distributions in A = 3 nuclei via 3He and 3H(e,e'p) measurements
    • R. Cruz-Torres, S. Li, F. Hauenstein, A. Schmidt, et al., (Jefferson Lab Tritium Collaboration)
    • arXiv:1902.06358 (2019)
Screen Shot 2019-02-22 at 2.23.35 PM.png

Important codes

During the experiment

The information that was more relevant for activities during the data-taking period will be moved from this page to the following new page:

Beam Energy Calibration

Done by D. Higinbotham (This is a 'pass-dependent' statement)

For second pass beam, use the Tiefenbach energy multiplied by 1.0025(5)

(That is, replace the value Ebeam in db_run.dat by 1.0025xEbeam)

After this correction, the measured Ebeam (before Eloss corrections) is ~ 4.3255 GeV

check this too

Raster Calibration

More details here

Target Information

Target density [mg/cm2]
Hydrogen 70.8 +/- 0.4
Deuterium 142.15 +/- 0.8
Tritium 85.1 +/- 0.8
Helium-3 53.4 +/- 0.6

Kinematics

MORE DETAILS HERE

These are the nominal values we got by optimizing in simc (these are not the actual values from the experiment)

Kinematics LHRS momentum [GeV] LHRS angle [deg] RHRS momentum [GeV] RHRS angle [deg]
Fast 3.543 20.88 1.4805 48.80
Slow 3.543 20.88 1.246 58.50
Parallel (Hydrogen) 3.543 17.80 1.4805 48.80

HRS Angles, Surveys, and Mispointings

LVDT retults

Kinematics Run number L mispointing [mm] R mispointing [mm] LHRS angle [deg] RHRS angle [deg]
Fast 100085 1.18245 -0.70915 20.8837 48.8207
Hydrogen 100100 0.9882 -0.7113 17.8017 48.8207
Slow 100532 0.48765 -0.65395 20.8812 58.5031
Fast2 100658 0.49145 -2.9875 20.8812 48.8187
Hydrogen2 100685 0.8831 -3.00255 17.8053 48.8188

HRS Momenta

Values taken from db_run.dat file.

Kinematics Run number LHRS p_cent [GeV] RHRS p_cent [GeV]
Fast 100085 3.54334 1.48051
Hydrogen 100102 3.54334 1.4805
Slow 100532 3.54331 1.246
Fast2 100658 3.5433 1.48051
Hydrogen2 100685 3.5433 1.4805

Optics

current LHRS matrix

current RHRS matrix

More information can be found here

Other information

  • BCM calibration
    • run number: 100172
    • target: carbon foil
    • currents and attenuator values:
      • 3uA ---> 140
      • 7uA ---> 163
      • 12uA ---> 184
      • 18uA ---> 204
      • 22.2uA ---> 214
    • These are nominal values for the beam current. Gotta get the actual values from epics info.
    • See example in the halog, entry number: 3505501
  • Unser calibration
    • run number: 100451
    • target: dummy
    • current values: 0,2,0,3,0,5,0,10,0,25,0,40,0,60,0,80,0,90,0,100,0,2,0,3,0,5,0,10,0 uA
    • Ideally we would have completed two full cycles from 0 to 100 uA, but the beam came back and we decided to go back to production.
    • See example in the halog, entry number: 3499263

Root files on Tape

Actual raw data: /mss/halla/triton/raw/

July 10th, 2018: /mss/halla/triton/prod/coinc_eep/pass2.1/all/

July 27th, 2018: /mss/halla/triton/prod/coinc_eep/pass2.2/all/

August 10th, 2018: /mss/halla/triton/prod/coinc_eep/pass2.3/all/

Documentation

Reference Reading

Previous (e,e'p) studies

Meetings

Bi-weekly Tritium SRC Analysis Meetings (Every Other Tuesdays 10:00 ET)

Weekly SRC Meetings (Wednesdays 9:30 ET)