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| | * Initial checks of beam position and raster. | | * Initial checks of beam position and raster. |
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| − | === HRS Checkout (Experts) === | + | ===[[ HRS Checkout (Experts) ]]=== |
| − | The detector checkout is best done using a fairly uniform illumination, which is
| + | |
| − | provided for by 20 μA on the central Carbon target at the following kinematics:
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| | | | |
| − | E' = 3.056 GeV, θ = 19 degrees (W<sup>2</sup> = 2.53 GeV, Q<sup>2</sup> = 2.43 GeV<sup>2</sup>). The
| + | ===[[ Beamline ]]=== |
| − | HRS electron rates should be about 270 Hz.
| + | |
| − | <table border="1" style="width:80%">
| + | |
| − | <tr>
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| − | <td>E<SUB>beam</SUB> [GeV]</td>
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| − | <td>P<sub>0</sub> [GeV/c]</td>
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| − | <td>θ<SUB>e</SUB> [deg]</td>
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| − | <td>Collimator</td>
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| − | <td>Target</td>
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| − | <td>Fast Raster <br> X x Y </td>
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| − | <td>Beam Current</td>
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| − | <td>Trigger</td>
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| − | </tr>
| + | |
| − | <tr>
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| − | <td>7.3</td>
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| − | <td>3.056</td>
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| − | <td>19.0</td>
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| − | <td>None</td>
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| − | <td>Single Carbon</td>
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| − | <td>off</td>
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| − | <td>20μA</td>
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| − | <td>S0&&S2m</td>
| + | |
| − | </tr>
| + | |
| − | </table>
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| − | <ol>
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| − | <li> With the above kinematics, take a run (at least 100K events or 10 minutes) and verify that all detector channels are working.
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| − | <li> Using the same run, produce a ROOT tree, and do the following: make a spectrum of x vs. y at the focal plane. What you should see is a "spider" with 5 legs. The non-straightness of the central legs indicates there is an offset in the Z or Y direction. If you don't see a "spider" or something resembling it, then of of the polarities of the HRS magnets is set wrong (or a magnet is off).
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| − | <li> Check that the signals are well timed.
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| − | <li> Determine correct thresholds.
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| − | <li> Verify all scalers are incrementing.
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| − | <li> Check for double pulsing and time the wire chamber signals.
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| − | <li> Are the scintillator signals for on scale in the scintillator ADCs?
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| − | <li> PID threshold checks.
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| − | </ol>
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| | | | |
| − | === Beamline === | + | ===[[ Beamline (2014) ]]=== |
| | | | |
| − | ==== Initial BPM/Raster checks/Beam centering ==== | + | ===[[ HRS Detector Calibrations ]]=== |
| − | <ol>
| + | |
| − | <li> First MCC centers the beam on the beam dump using the ion chambers.
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| − | <li> Ideally the beam should be able to pass cleanly through the Compton chicane. But this is not a requirement.
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| − | <li>Check the raster size using the spot++ tool. After the target boiling studies result, the final raster size for production data will be decided.<br>
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| − | <li>Insert carbon hole target to center the beam position with respect to the hole. Setup the raster to 2*2 mm, use spot++ to check if the beam is centered around the hole. Move the beam if necessary.
| + | |
| − | </ol>
| + | |
| | | | |
| − | ==== Superharp Scan with Raster off/on ==== | + | ===[[ Beam Position on Target ]]=== |
| − | <ol>
| + | |
| − | <li> Scan the two superharps near the target with raster off. Obtain two pictures including the three wires for each harp.
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| − | <li> Make sure the three wires are clearly visible and have reasonable resolution: ~ 100-200 μm.
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| − | <li> Repeat with raster on. In this case, you may not see the wires clearly.
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| − | <li> Make sure to post the results in the Hall A electronic logbook or Halog.
| + | |
| − | </ol>
| + | |
| − | | + | |
| − | ==== BPM Calibrations (Bullseye Scan) ====
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| − | <FONT Color="Green">How to perform a bulls eye scan</FONT>:
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| − | | + | |
| − | 1. You need unrastered beam:
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| − | - <FONT Color="red">caution you should not do this with a target requiring rastered beam</FONT>
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| − | - use carbon, BeO, optics, or in the worst case empty instead
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| − | | + | |
| − | 2. Ask MCC to steer the beam to the nominal center of the target.
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| − | | + | |
| − | 3. Wait until beam is stable and have MCC perform a harp scan for the two superharps near the target (1H03A and 1H03B) and take a coda run during the
| + | |
| − | same time. Start the coda run first before asking MCC. Request MCC to make an ELOG entry with the results, you should see all three harp wires.
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| − | Record ELOG entry numbers.
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| − | | + | |
| − | 4. Ask MCC then to steer the beam to positions around the nominal center:
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| − | - cover at least the area the raster will cover: (2,2), (2,-2), (-2,-2), (-2,2) and repeat (0,0)
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| − | - repeat harp and coda runs for each position
| + | |
| − | | + | |
| − | 5. Record Harp scan run numbers and corresponding CODA run number for each beam position.
| + | |
| − | | + | |
| − | 6. Make a record of the harp scans and CODA runs in the HAlog.
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| − | | + | |
| − | <FONT Color="Green">How to analyze the bulls eye scan</FONT>:
| + | |
| − | - detailed instructions can be found at the [http://hallaweb.jlab.org/root/doc/bpm.html Analyzing BPMs] website.
| + | |
| − | - <FONT Color="red">the shift crew is not expected to analysis the bulls eye scan</FONT>.
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| − | | + | |
| − | ==== BCM Calibrations [2 hours] ====
| + | |
| − | <ol>
| + | |
| − | <li> Warn MCC a few hours beforehand.
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| − | <li> The Hall A BCM and scalers need to be cross-calibrated to the Faraday cup and a BCM in the accelerator (OLO2) and the Hall A Unser.
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| − | <li> Before beginning the procedure, make sure the Hall A BCM logger is started, which will record the signals from all relevant BCM used during the calibration.
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| − | <li> Also start a HRS run to record the scalers during the calibration procedure.
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| − | <li> It is useful to have someone over in MCC to help coordinate the calibration with them.
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| − | <li> Take data on carbon target with I = 10, 20, 30, 40 50, 60, 70, 80, 90, 100 μA (or as high a current as available).
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| − | </ol>
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| − | | + | |
| − | ==== ARC Energy Measurement [? hours] ====
| + | |
| − | <ol>
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| − | <li> The procedure will be conducted by Doug Higinbotham in coordination with MCC.
| + | |
| − | <li> Notify Doug and MCC a few hours beforehand to make sure they are ready and available.
| + | |
| − | </ol>
| + | |
| | | | |
| | ===[[ Spectrometer Optics ]]=== | | ===[[ Spectrometer Optics ]]=== |
| | | | |
| | + | ===[[ Spectrometer Optics 2014 ]]=== |
| | | | |
| | + | === [[ Luminosity Scans - Low Rate (Target Boiling) ]]=== |
| | | | |
| − | | + | === [[ Initial HRS Elastic Checks ]]=== |
| − | | + | |
| − | | + | |
| − | | + | |
| − | | + | |
| − | === [[ Luminosity Scans - Low Rate (Target Boiling) ]]=== | + | |
The following items should be performed during the first 1-1.5 shifts with beam on target:
