Difference between revisions of "Spectrometer Optics"

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 +
==== Procedure without Sieve-slit ====
 +
* Time estimate: 4 hours
 +
 +
* Take a run at the following kinematics without the sieve-slit collimator on the <b>multi-foil carbon target</b>.
 +
* Start with initial right HRS spectrometer tune with the SOS quad in place of right Q1.
 +
* 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.
 +
* <b>A GMp expert will check the data quality and decide, if the right HRS tune needs to be adjusted to change the size of the acceptance.</b>
 +
* This process will be repeated until the spectrometer tune is satisfactory.<br>
 +
 +
<table border="1"  style="width:80%">
 +
  <tr>
 +
    <td>E<SUB>beam</SUB> [GeV]</td>
 +
    <td>P<sub>0</sub> [GeV/c]</td>
 +
    <td>&theta;<SUB>e</SUB> [deg]</td>
 +
    <td>Q<SUP>2</SUP> [GeV<SUP>2</SUP>]</td>
 +
    <td>W [GeV]</td>
 +
    <td> Rate [Hz] at 20 &mu;A</td>
 +
    <td> minutes for 300k events at 20 &mu;A</td>
 +
  </tr>
 +
  <tr>
 +
    <td>3.8</td>
 +
    <td>1.002</td>
 +
    <td>33.0</td>
 +
    <td>1.23</td>
 +
    <td>2.214</td>
 +
    <td>316</td>
 +
    <td>16</td>
 +
  </tr>
 +
</table>
 +
 
==== Procedure with Sieve-slit ====
 
==== Procedure with Sieve-slit ====
 
* Time estimate: 1-2 hours
 
* 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.
+
  * Trained personnel will be required to install the 1-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.
+
  * Take a sieve slit run with the <b>multi-foil carbon target</b> 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.
 
  * 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.
 
  * 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.
+
  * Rates assume 5 carbon foils, only 25 out of 63 sieve holes have events (~ 0.265 mSr acceptance), and 9% delta acceptance.
−
 
+
* Note: <b>if the right HRS minimum angle is 35 degrees instead of 33 degrees, then the rate will be ~ 50 Hz instead</b>.
 
<table border="1"  style="width:80%">
 
<table border="1"  style="width:80%">
 
   <tr>
 
   <tr>
Line 16: Line 47:
 
     <td>W [GeV]</td>
 
     <td>W [GeV]</td>
 
     <td> Rate [Hz] at 20 &mu;A</td>
 
     <td> Rate [Hz] at 20 &mu;A</td>
−
     <td> minutes for 100k events at 20 &mu;A</td>
+
     <td> minutes for 90k events at 20 &mu;A</td>
 
   </tr>
 
   </tr>
 
   <tr>
 
   <tr>
−
     <td>7.3</td>
+
     <td>3.8</td>
−
     <td>3.200</td>  
+
     <td>1.002</td>  
−
     <td>19.0</td>
+
     <td>33.0</td>
−
     <td>2.5</td>
+
     <td>1.23</td>
−
    <td>2455</td>
+
     <td>2.214</td>
−
    <td>15</td>
+
     <td>17</td>
−
    <td>110</td>
+
     <td>90</td>
−
  </tr>
+
−
  <tr>
+
−
    <td>7.3</td>
+
−
     <td>2.019</td>
+
−
    <td>19.0</td>
+
−
    <td>1.6</td>
+
−
    <td>3030</td>
+
−
     <td>24</td>
+
−
     <td>70</td>
+
 
   </tr>
 
   </tr>
 
</table>
 
</table>
  
−
<b>Alternative rates with 1-inch tungsten sieve slit: </b>
+
==== Delta Scan with Hydrogen Elastic ====
−
  * Assumes that 49 out of the 63 holes are seen (~ 0.52 mSr acceptance); however, the acceptance is reduced by 85%, <br> since not all foils will see all holes.
+
* Time estimate: 2-3 hours
−
  * Rates assume 5 carbon foils and 9% delta acceptance.
+
 
 +
* Trained personnel will be required to remove the 1-inch lead sieve-slit collimator onto the front face of the HRS.
 +
  * Take a run with the 15 cm liquid hydrogen target for the elastic kinematics in the table.
 +
  * There will be a time lapse between settings until the right dipole reaches the desired momentum and is stable.
 +
  * If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.<br>
 +
 
 
<table border="1"  style="width:80%">
 
<table border="1"  style="width:80%">
 
   <tr>
 
   <tr>
−
     <td>E<SUB>beam</SUB> [GeV]</td>
+
     <td>E<SUB>beam</SUB> (GeV)</td>
−
     <td>P<sub>0</sub> [GeV/c]</td>  
+
     <td>k' (GeV)</td>  
−
     <td>&theta;<SUB>e</SUB> [deg]</td>
+
     <td>&theta;<SUB>e</SUB> (deg)</td>
−
     <td>Q<SUP>2</SUP> [GeV<SUP>2</SUP>]</td>
+
     <td>&Delta;P (%)</td>
−
    <td>W [GeV]</td>
+
 
     <td> Rate [Hz] at 20 &mu;A</td>
 
     <td> Rate [Hz] at 20 &mu;A</td>
−
    <td> minutes for 200k events at 20 &mu;A</td>
+
    <td> minutes for 10k events at 20 &mu;A</td>
 
   </tr>
 
   </tr>
 
   <tr>
 
   <tr>
−
     <td>7.3</td>
+
     <td>3.8</td>
−
     <td>3.056</td>  
+
    <td>2.39025</td>
−
     <td>19.0</td>
+
    <td>33.0</td>
−
     <td>2.4</td>
+
    <td>-4</td>
−
     <td>2533</td>
+
    <td>6</td>
−
     <td>58</td>
+
    <td>30</td>
−
     <td>58</td>
+
  </tr>
 +
  <tr>
 +
    <td>3.8</td>
 +
    <td>2.34429</td>
 +
    <td>33.0</td>
 +
    <td>-2</td>
 +
    <td>6</td>
 +
    <td>30</td>
 +
  </tr>
 +
  <tr>
 +
     <td>3.8</td>
 +
     <td>2.29832</td>
 +
    <td>33.0</td>
 +
    <td>0</td>
 +
    <td>6</td>
 +
    <td>30</td>
 +
  </tr>
 +
  <tr>
 +
    <td>3.8</td>
 +
     <td>2.25235</td>  
 +
     <td>33.0</td>
 +
    <td>+2</td>
 +
    <td>6</td>
 +
    <td>30</td>
 +
  </tr>
 +
  <tr>
 +
    <td>3.8</td>
 +
    <td>2.20639</td>
 +
    <td>33.0</td>
 +
    <td>+4</td>
 +
     <td>6</td>
 +
     <td>30</td>
 
   </tr>
 
   </tr>
 
</table>
 
</table>
  
 
==== Elastic from Hydrogen ====
 
==== Elastic from Hydrogen ====
 +
* Time estimate: 1-2 hours
  
−
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.<br> (Table borrowed from DVCS3 wiki page)<br>
+
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
 +
* Elastic electron-proton measurement.  Assuming a 15 cm LH2 target, a spectrometer acceptance of 5 msr and elastic from Eric's rate program <br>
 +
  to compute the cross-section.<br>
 
<table border="1"  style="width:80%">
 
<table border="1"  style="width:80%">
 
   <tr>
 
   <tr>
 
     <td>E<SUB>beam</SUB> (GeV)</td>
 
     <td>E<SUB>beam</SUB> (GeV)</td>
−
     <td>k' (GeV)</td>  
+
     <td>e' (GeV)</td>  
 
     <td>&theta;<SUB>e</SUB> (deg)</td>
 
     <td>&theta;<SUB>e</SUB> (deg)</td>
 
     <td>Q<SUP>2</SUP> (GeV<SUP>2</SUP>)</td>
 
     <td>Q<SUP>2</SUP> (GeV<SUP>2</SUP>)</td>
 
     <td> Rate [Hz] at 20 &mu;A</td>
 
     <td> Rate [Hz] at 20 &mu;A</td>
−
     <td> minutes for 5.4k events at 20& mu;A</td>
+
     <td> minutes for 20.6k events at 20 &mu;A</td>
 
   </tr>
 
   </tr>
−
<tr>
+
  <tr>
−
     <td>7.3</td>
+
     <td>3.8</td>
−
     <td>3.2</td>  
+
     <td>2.29832</td>  
−
     <td>33.4</td>
+
     <td>33.0</td>
−
     <td>7.7</td>
+
     <td>2.82</td>
−
     <td>1.5</td>
+
     <td>6</td>
 
     <td>60</td>
 
     <td>60</td>
 
   </tr>
 
   </tr>
 
   <tr>
 
   <tr>
−
     <td>5.5</td>
+
     <td>2.056</td>
−
     <td>3.2</td>  
+
     <td>1.706</td>
−
     <td>28.7</td>
+
    <td>25.0</td>
−
     <td>4.3</td>
+
    <td></td>
−
     <td>15</td>
+
    <td></td>
−
     <td> 6</td>
+
    <td></td>
 +
  </tr>
 +
  <tr>
 +
    <td>2.056</td>
 +
     <td>1.192</td>  
 +
     <td>48.7</td>
 +
    <td></td>
 +
     <td></td>
 +
     <td></td>
 
   </tr>
 
   </tr>
 
</table>
 
</table>

Latest revision as of 15:22, 29 April 2015

Procedure without Sieve-slit

  • Time estimate: 4 hours
* Take a run at the following kinematics without the sieve-slit collimator on the multi-foil carbon target.
* Start with initial right HRS spectrometer tune with the SOS quad in place of right Q1.
* 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.
* A GMp expert will check the data quality and decide, if the right HRS tune needs to be adjusted to change the size of the acceptance.
* This process will be repeated until the spectrometer tune is satisfactory.
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 300k events at 20 μA
3.8 1.002 33.0 1.23 2.214 316 16

Procedure with Sieve-slit

  • Time estimate: 1-2 hours
* Trained personnel will be required to install the 1-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 25 out of 63 sieve holes have events (~ 0.265 mSr acceptance), and 9% delta acceptance.
* Note: if the right HRS minimum angle is 35 degrees instead of 33 degrees, then the rate will be ~ 50 Hz instead.
Ebeam [GeV] P0 [GeV/c] θe [deg] Q2 [GeV2] W [GeV] Rate [Hz] at 20 μA minutes for 90k events at 20 μA
3.8 1.002 33.0 1.23 2.214 17 90

Delta Scan with Hydrogen Elastic

  • Time estimate: 2-3 hours
* Trained personnel will be required to remove the 1-inch lead sieve-slit collimator onto the front face of the HRS.
* Take a run with the 15 cm liquid hydrogen target for the elastic kinematics in the table.
* There will be a time lapse between settings until the right dipole reaches the desired momentum and is stable.
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
Ebeam (GeV) k' (GeV) θe (deg) ΔP (%) Rate [Hz] at 20 μA minutes for 10k events at 20 μA
3.8 2.39025 33.0 -4 6 30
3.8 2.34429 33.0 -2 6 30
3.8 2.29832 33.0 0 6 30
3.8 2.25235 33.0 +2 6 30
3.8 2.20639 33.0 +4 6 30

Elastic from Hydrogen

  • Time estimate: 1-2 hours
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
* Elastic electron-proton measurement.  Assuming a 15 cm LH2 target, a spectrometer acceptance of 5 msr and elastic from Eric's rate program 

  to compute the cross-section.
Ebeam (GeV) e' (GeV) θe (deg) Q2 (GeV2) Rate [Hz] at 20 μA minutes for 20.6k events at 20 μA
3.8 2.29832 33.0 2.82 6 60
2.056 1.706 25.0
2.056 1.192 48.7
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