<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear All:</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I'd like to point out that the polarized 3He target cell used by the A1n/d2n experiment is a fragile, high-pressure gas cell. You do not see it when taking shifts, but they are pressurized to 10-12atm, with glass walls 1mm thick and glass windows (where the
beam comes through) 150um thick. It is for this reason we must raster the beam to a specific size, and any movement in the beam position will have a chance of damaging the cell.
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<b><span style="color: rgb(94, 50, 124); background-color: rgb(255, 255, 0);"><u><i>Please follow beam recovery procedure closely:</i></u></span></b></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<a href="https://hallcweb.jlab.org/wiki/index.php/Beam_and_Raster_Checkout_for_A1n/d2n_(Short_Procedure)" id="LPlnk208467">https://hallcweb.jlab.org/wiki/index.php/Beam_and_Raster_Checkout_for_A1n/d2n_(Short_Procedure)</a></div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
A printed copy is usually available at the Shift Leader console in the counting house.
<u><b><span style="color: rgb(200, 38, 19);">Please </span><span style="color: rgb(200, 38, 19);">r</span><span style="color: rgb(200, 38, 19);">ead and follow</span></b>.</u><br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt">
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt">
--<b>Do not ever</b> skip the beam recovery procedure for the sake of "taking more production data".</div>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
--<b>Do not ever </b>allow MCC to send CW beam on polarized 3He cell without first completing the procedure. (And project/calculate the beam size at the target, the harp scan values are not enough.
<b>The sigmas at the target cannot be larger than 500 micrometers</b>).<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
--<b>Do not ever</b> ask for or suggest raster size smaller than 4.0mm diameter on the polarized 3He or the reference cell positions.<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
--Most importantly, <b>if in doubt (on anything), contact the RC for confirmation</b>.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Also, a screenshot of the Operation Restrictions is posted on the experimental wiki page:
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<a href="https://hallcweb.jlab.org/wiki/index.php/File:PolHe3-operational-restrictions.png">
https://hallcweb.jlab.org/wiki/index.php/File:PolHe3-operational-restrictions.png</a><br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
All shift crews (RCs, SLs and TOs) please become familiar with these restrictions. Whatever beam you ask from the MCC should conform to these restrictions.
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Thanks for listening.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Xiaochao<br>
</div>
</body>
</html>