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Dear TPEers,<br>
<br>
We will need to decide how often to reverse the magnetic fields. There
are a few constraints.<br>
<ol>
<li>we should reverse torus fields weekly during the Tuesday
maintenance period</li>
<li>we need to remeasure the two beam energy vs position after
reversing the chicane. This will take about 4 hours.</li>
</ol>
We should decide whether to switch the chicane when we switch the torus
or not.<br>
<br>
There are generally two schemes: 1) switch both the torus and the
chicane weekly, but out of phase or 2) switch the torus weekly and the
chicane every other week.<br>
<br>
Scheme 1: switch torus polarities on Tuesdays (during maintenance
periods) and switch chicane polarities on Fridays. <br>
Advantages: a) complete set of four field possibilities every two
weeks, b) reverse Torus fields during down times, c) never change both
fields together <br>
Disadvantage: must measure beam distributions every week with the
calorimeter and dense fiber monitor<br>
<table width="50%" cellspacing="2" cellpadding="2" border="1">
<tbody>
<tr>
<td valign="top">day<br>
</td>
<td valign="top">torus <br>
polarity<br>
</td>
<td valign="top">chicane<br>
polarity<br>
</td>
</tr>
<tr>
<td valign="top">1 Tuesday<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">+<br>
</td>
</tr>
<tr>
<td valign="top">4 Friday<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">-<br>
</td>
</tr>
<tr>
<td valign="top">8 Tuesday<br>
</td>
<td valign="top">-<br>
</td>
<td valign="top">-<br>
</td>
</tr>
<tr>
<td valign="top">11 Friday<br>
</td>
<td valign="top">-<br>
</td>
<td valign="top">+<br>
</td>
</tr>
<tr>
<td valign="top">15 Tuesday<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">+<br>
</td>
</tr>
</tbody>
</table>
<br>
Scheme 2: switch torus polarities on Tuesdays (during maintenance
periods) and switch chicane polarities on alternate Tuesdays (or
Fridays). <br>
Advantages: a) reverse Torus fields during down times, b) measure beam
distributions every two weeks<br>
Disadvantages: a) complete set of four field possibilities every four
weeks, b) change both fields on the same day (if done Tuesday)<br>
<table width="50%" cellspacing="2" cellpadding="2" border="1">
<tbody>
<tr>
<td valign="top">day<br>
</td>
<td valign="top">torus<br>
polarity<br>
</td>
<td valign="top">chicane<br>
polarity<br>
</td>
</tr>
<tr>
<td valign="top">1 Tuesday<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">+<br>
</td>
</tr>
<tr>
<td valign="top">8 <br>
</td>
<td valign="top">-<br>
</td>
<td valign="top">+<br>
</td>
</tr>
<tr>
<td valign="top">15<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">-<br>
</td>
</tr>
<tr>
<td valign="top">22<br>
</td>
<td valign="top">-<br>
</td>
<td valign="top">-<br>
</td>
</tr>
<tr>
<td valign="top">29<br>
</td>
<td valign="top">+<br>
</td>
<td valign="top">+<br>
</td>
</tr>
<tr>
<td valign="top">36<br>
</td>
<td valign="top">-<br>
</td>
<td valign="top">+<br>
</td>
</tr>
</tbody>
</table>
<br>
The frequency of beam distribution measurements will have an impact on
calorimeter mounting. <br>
<br>
<pre cols="72" class="moz-signature">--
Sincerely,
Larry
-----------------------------------------------------------
Lawrence Weinstein
University Professor
Physics Department
Old Dominion University
Norfolk, VA 23529
757 683 5803
757 683 3038 (fax)
<a href="mailto:weinstein@odu.edu">weinstein@odu.edu</a>
<a href="http://www.lions.odu.edu/~lweinste/">http://www.lions.odu.edu/~lweinste/</a></pre>
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