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<b><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt;">Don't Worry, Be Happy.</span></b></div>
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<b><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt;">Don't Worry, Be Happy.</span></b></div>
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<div><span style="font-family: Calibri, Helvetica, sans-serif;">Ever since the first
</span><span style="font-family: Calibri, Helvetica, sans-serif;"><span style="font-family: Calibri, Helvetica, sans-serif">polarized 3He
</span></span><span style="font-family: Calibri, Helvetica, sans-serif;">electron scattering experiment, E142 at SLAC, people have been naming these glass cells. Well, how else would you tell these nearly identical glass cells apart? By their exchange symmetry
properties??</span><br>
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<div><span style="font-size: 10pt; font-family: Tahoma, Geneva, sans-serif;"><b>Don't Worry</b></span> and
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt;"><b>Be Happy</b></span> are the names of the two first glass cells used in the GDH experiment in Hall A. You don't have to ask how the experiment went: Just look at these names, they **scream**
the challenge of installing and running this target at JLab the first time. <span style="font-size: 10pt; font-family: Tahoma, Geneva, sans-serif">
<b>Don't Worry</b></span> showed a ~25% in-beam polarization and lasted about 8 days.
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Be Happy</b></span> lasted less than 4 days, mid-30% in-beam. How many cells were used by GDH? Even the then Ph.D. thesis student of GDH (the current Hall C Run Coordinator) does not
know by heart: "We lost count, they just kept exploding", he said. And one should not forget cell
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Blue</b></span>.
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Blue</b></span> did not even show up in typical documentation of GDH, not even in PhD theses.
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Blue</b></span> was installed in the target chamber without problem, but exploded right after because of unrastered beam and no physics data was taken with it. For reference, these glass
cells did not need rastering under the pulsed beam of SLAC.<br>
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<span style="font-family: Calibri, Helvetica, sans-serif;">A lot has been learned on the electron beam effect on these glass cells since then. For example, it was found that each cell in average lasts about one month in beam. After that, radiation effect darkens
the glass enough to cause increased laser absorption by the glass, and the cell would have a high chance of rupturing. The common wisdom from 6 GeV time is that the cell needs changed proactively after one month worth of running
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<span style="font-family: Calibri, Helvetica, sans-serif;">(or RadCon would have a busy time removing irradiated glass shapnels). But does our 6 GeV wisdom apply to the higher beam energy and current? Although simulation shows similar radiation from 30uA 12
GeV beam to 15uA 6 GeV beam, thanks to the improved cell design, we were not so sure... until now.
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<span style="font-family: Calibri, Helvetica, sans-serif;">On Monday Feb. 10th, cell
</span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt;"><b>Dutch</b></span><span style="font-family: Calibri, Helvetica, sans-serif;"> will b<span style="font-family: Calibri, Helvetica, sans-serif"></span><span style="font-family: Calibri, Helvetica, sans-serif"><span><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"></span></span></span></span><span style="font-family: Calibri, Helvetica, sans-serif"><span><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"></span></span></span></span><span style="font-family: Calibri, Helvetica, sans-serif"><span><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"></span></span></span></span>e<span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"></span></span>
officially retired. By then it will have seen beam for 31 days, most of which is 30uA at 10.4 GeV. Amazingly,
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Dutch</b></span><span style="font-family: Calibri, Helvetica, sans-serif"></span> polarization has not shown any sign of degradation in the most recent week, still holding at 60%+/50%+
in the transverse/longitudinal direction. We do not know yet why the longitudinal polarization is not as high as that in transverse. Could it be that beam irradiation has caused more darkening of the glass in the longitudinal pumping direction? Or is it something
else? After all, with 30uA we are venturing into a new terrain of running these polarized 3He cells. After the target enclosure is opened on Monday, the first thing our target experts plan to do is a visual inspection of
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Dutch</b></span><span style="font-family: Calibri, Helvetica, sans-serif"></span>, and maybe we will solve the mystery then.</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">Following the removal of
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Dutch</b></span><span style="font-family: Calibri, Helvetica, sans-serif"></span>, new cell
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>BigBrother</b></span></b></span> will be installed and used for the remainder (fingers crossed) running of A1n.
In laboratory settings, <span style="font-family: Calibri, Helvetica, sans-serif">
<span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span><b>BigBrother</b></span></b></span></span>has shown even higher polarization than
<span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Dutch</b></span><span></span></span>, and we are keeping our hope high for its in-beam performance as well. On Tuesday, while
<span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span><b>BigBrother</b></span></b></span></span> is being pumped to build up polarization, we will carry out 24 hours worth of
reference cell runs that are needed by the experiment.</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">This is an exciting time, however,
<i>we can't do everything without your help</i>. </span><span style="font-family: Calibri, Helvetica, sans-serif; background-color: rgb(255, 255, 0);"><u>We are in dire need of shift workers for the upcoming week, most urgently Tuesday Swing; Wednesday Owl
and Swing, and Thursday Owl and Swing</u></span><span style="font-family: Calibri, Helvetica, sans-serif; background-color: rgb(255, 255, 0);">.</span><span style="font-family: Calibri, Helvetica, sans-serif;">
<b>Please come join us.</b> <i>If you sign up for Tuesday swing, you will possibly witness the removal of</i><b>
<span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b>Dutch</b></span><span></span></span>
</b><i>and observe the first spinup of </i><b><span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span style="font-family: Calibri, Helvetica, sans-serif"><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span><b>BigBrother</b></span></b></span></span></span></b></span></span></b><span style="font-family: Calibri, Helvetica, sans-serif"><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><span style="font-family: Calibri, Helvetica, sans-serif"><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><span><i></i></span></span></span></span></span></span><i>
</i>(all while taking a disk load of data on the reference cell).<b> </b><i>If you sign up for Wednesday Owl/Swing or Thursday Owl/swing,</i><i> you will possibly be the one putting beam on
</i><b><span style="font-family: Calibri, Helvetica, sans-serif"><span><span style="font-family: Tahoma, Geneva, sans-serif; font-size: 10pt"><b><span><b>BigBrother</b></span></b></span></span></span></b> the first time.
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<span style="font-family: Calibri, Helvetica, sans-serif;">This will be a historical time, don't miss the chance of making yourself a part of the history. After all, it is only one click away! (Tip: see shift sign-up link below).</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;"><span style="font-family: Calibri, Helvetica, sans-serif"><b>
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<span style="font-family: Calibri, Helvetica, sans-serif"><a href="https://misportal.jlab.org/mis/physics/shiftSchedule/?experimentRunId=HALLC-POL3HE">https://misportal.jlab.org/mis/physics/shiftSchedule/?experimentRunId=HALLC-POL3HE</a></span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">(not your usual) spokesperson of A1n</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">Xiaochao</span><br>
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