Difference between revisions of "Spectrometer Optics"

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(→‎Elastic from Hydrogen)
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     <td>58</td>
 
     <td>58</td>
 
   </tr>
 
   </tr>
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</table>
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==== Procedure without Sieve-slit ====
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 +
* Next take a run at the following kinematics without the sieve-slit collimator.
 +
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
 +
* Rates assume 5 carbon foils, 6 mSr acceptance, and 9% delta acceptance.
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<table border="1"  style="width:80%">
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-
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  <tr>
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-
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    <td>E<SUB>beam</SUB> [GeV]</td>
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+
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-
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    <td>P<sub>0</sub> [GeV/c]</td>
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+
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-
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    <td>&theta;<SUB>e</SUB> [deg]</td>
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+
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-
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    <td>Q<SUP>2</SUP> [GeV<SUP>2</SUP>]</td>
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+
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-
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    <td>W [GeV]</td>
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-
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    <td> Rate [Hz] at 20 &mu;A</td>
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-
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    <td> minutes for 400k events at 20 &mu;A</td>
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-
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  </tr>
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-
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  <tr>
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-
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    <td>7.3</td>
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-
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    <td>3.200</td>
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+
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-
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    <td>19.0</td>
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+
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-
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    <td>2.5</td>
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+
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-
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    <td>2455</td>
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+
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-
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    <td>623</td>
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+
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-
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    <td>11</td>
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+
 +
-
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  </tr>
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+
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-
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  <tr>
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+
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-
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    <td>7.3</td>
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+
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-
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    <td>2.019</td>
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+
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-
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    <td>19.0</td>
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+
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-
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    <td>1.6</td>
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+
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-
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    <td>3030</td>
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+
 +
-
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    <td>975</td>
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+
 +
-
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    <td>7</td>
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+
 +
-
 +
  </tr>
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+
 +
-
 
</table>
 
</table>
  

Revision as of 16:37, 16 October 2014

Procedure with Sieve-slit

  • Time estimate: 1-2 hours
* A Hall A Tech may be required to install the 2-inch lead sieve-slit collimator onto the front face of the HRS.
* Take a sieve slit run with the multi-foil carbon target for the inelastic kinematics in the table.
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
* Repeat the above with the beam position shifted so that you see a vertical shift by one row.
* Rates assume 5 carbon foils, only 9 out of 25 sieve holes have events (~ 0.146 mSr acceptance), and 9% delta acceptance.
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 100k events at 20 μA
7.3 3.200 19.0 2.5 2455 15 110
7.3 2.019 19.0 1.6 3030 24 70 
Alternative rates with 1-inch tungsten sieve slit: 
* Assumes that 49 out of the 63 holes are seen (~ 0.52 mSr acceptance); however, the acceptance is reduced by 85%, 
  since not all foils will see all holes.
* Rates assume 5 carbon foils and 9% delta acceptance.
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 200k events at 20 μA
7.3 3.056 19.0 2.4 2533 58 58

Procedure without Sieve-slit

  • Next take a run at the following kinematics without the sieve-slit collimator.
  • If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
  • Rates assume 5 carbon foils, 6 mSr acceptance, and 9% delta acceptance.
+ - + -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ - + -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ - + -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 400k events at 20 μA
7.3 3.200 19.0 2.5 2455 623 11
7.3 2.019 19.0 1.6 3030 975 7

Elastic from Hydrogen

Elastic electron-proton measurement. Assuming a 15 cm LH2 target, a spectrometer acceptance of 6 msr and elastic from Eric's rate program to compute the cross-section. Taking data at 7.3 GeV with the given momentum restrictions is time consuming.
(Table borrowed from DVCS3 wiki page)

Ebeam (GeV) k' (GeV) θe (deg) Q2 (GeV2) Rate [Hz] at 20 μA minutes for 5.4k events at 20 μA
7.3 3.2 33.4 7.7 1.5 60
5.5 3.2 28.7 4.3 15 6
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