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<p style="margin-top:0; margin-bottom:0">Hi Matt, <br>
</p>
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">Here is a link to the meeting in case you cannot be in the counting house at 5pm:</p>
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<font size="2"><span style="font-size:11pt;"><font size="2"><span style="font-size:11pt;">Bluejeans link: <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjlab.bluejeans.com%2F7572695553&data=02%7C01%7Cprimexd%40jlab.org%7Cf9422a10c93d47bce90708d69dc47cd0%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C1%7C636869864566934392&sdata=rPL6fVZFwBiUPct%2BN4XVJJzrhcG9k95Jtxi%2FQt0vFrM%3D&reserved=0" originalSrc="https://jlab.bluejeans.com/7572695553" shash="G7SMM1+L/NzDvCesEDQka8I1yMEFa6mUiXliUh6UzkE4zGJh7FSWo+TJGNDVw+7x9n1zCQlReG22rXBxcFSQ9fNLkT83MMcC0duaG30HPPdF0MVnJ4FVjgGDXGYmnIyNVkiVcC339xcmow29i4bF+TBJES6gvT45sfSr39s+JFo=" target="_blank" rel="noopener noreferrer" data-auth="NotApplicable" id="LPlnk230022" previewremoved="true">https://jlab.bluejeans.com/7572695553</a></span></font></span></font></p>
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<font size="2"><span style="font-size:11pt;">Best,</span></font></p>
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<font size="2"><span style="font-size:11pt;">- Drew<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Primexd <primexd-bounces@jlab.org> on behalf of gasparan@jlab.org <gasparan@jlab.org><br>
<b>Sent:</b> Thursday, February 28, 2019 4:19:16 PM<br>
<b>To:</b> Shepherd, Matthew<br>
<b>Cc:</b> primexd@jlab.org; Simon Taylor; andrsmit@jlab.org; Mark Stevens<br>
<b>Subject:</b> Re: [Primexd] [GlueX] Target installation plan</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt">
<div class="PlainText"><br>
Matt,<br>
Please try to be at the 5 pm meeting and we discuss them.<br>
<br>
If the FCAL is shadowing the CCAL then no software alignment<br>
will give us a reasonable statistics.<br>
<br>
Thanks,<br>
Ashot<br>
<br>
<br>
> Ashot,<br>
><br>
>> What we have is a Large asymetry.<br>
>> I think we have to understand how to solve it to go forward with the<br>
>> data taking process.<br>
><br>
><br>
> You solve the asymmetry by aligning your detector not with the beam line<br>
> as you have done now but instead the FCAL beam hole.<br>
><br>
> Unfortunately, doing so means that you significantly change the acceptance<br>
> of your detector. And because of that you may want to reconsider taking<br>
> the data you have collected already.<br>
><br>
> The cause seems pretty clear -- you just need a strategy that let's you<br>
> make the measurement with acceptable systematic uncertainties.<br>
><br>
> I suspect you'll see the same effect in your December data also.<br>
><br>
> Matt<br>
><br>
><br>
>> On Feb 28, 2019, at 4:06 PM, gasparan@jlab.org wrote:<br>
>><br>
>><br>
>> Matt, before I go through your email and try to discuss, one thing<br>
>> we have to take care of is the real data.<br>
>> We probably agree that in order to have better and usable data the<br>
>> acceptances need to be symmetrical. What we have is a Large asymetry.<br>
>> I think we have to understand how to solve it to go forward with the<br>
>> data taking process.<br>
>><br>
>> let's discuss this in today's meeting.<br>
>><br>
>> Thanks,<br>
>> Ashot<br>
>><br>
>>><br>
>>> Ashot,<br>
>>><br>
>>> I don't think a survey of the beam line is needed. I think you just<br>
>>> need<br>
>>> to use the existing survey.<br>
>>><br>
>>> I realized that it completely explains your asymmetry.<br>
>>><br>
>>> As Justin noted, the Compton image on the CCAL is exactly as you<br>
>>> predict,<br>
>>> just shifted by 2 cm. What I neglected in my previous message is that<br>
>>> if<br>
>>> you make a shift of CCAL by 1 cm you effectively shift the image by 2<br>
>>> cm.<br>
>>> In your reconstruction, shifting CCAL to +x by 1 cm will make the<br>
>>> Compton<br>
>>> occupancy go from -9 cm to +9 cm on the CCAL (instead of -8 cm to + 10<br>
>>> cm).<br>
>>><br>
>>> Now, if you need to shift CCAL by 1 cm, it means that, because of the<br>
>>> lever arm, the FCAL is shifted about 5 mm to +X. This is exactly as<br>
>>> reported by Simon. And there is no vertical offset, also as reported<br>
>>> by<br>
>>> Simon.<br>
>>><br>
>>> Seems the conclusion is straightforward:<br>
>>><br>
>>> Your asymmetry of Compton events is not related to excess material in<br>
>>> the<br>
>>> beam line, or bugs in reconstruction, it is byproduct of the already<br>
>>> known<br>
>>> alignment of the FCAL with respect to the beam line. Again, working<br>
>>> with<br>
>>> simulation done in the Hall D framework will demonstrate these effects.<br>
>>><br>
>>> Seems like you have two choices now:<br>
>>><br>
>>> * Align CCAL not on beam center but on FCAL hole center. But then you<br>
>>> may<br>
>>> want to retake Be data.<br>
>>> * Live with existing alignment and explore systematics.<br>
>>><br>
>>> Matt<br>
>>><br>
>>><br>
>>>> On Feb 28, 2019, at 3:48 PM, gasparan@jlab.org wrote:<br>
>>>><br>
>>>><br>
>>>> Dear Matt and All,<br>
>>>><br>
>>>> At this stage it is clear that we should survey entire beam line,<br>
>>>> for sure including the FCAL (not only CCAL).<br>
>>>><br>
>>>> The question is what to do next.<br>
>>>><br>
>>>> Ashot<br>
>>>><br>
>>>><br>
>>>>><br>
>>>>> Liping,<br>
>>>>><br>
>>>>> Without survey I cannot definitively assert that it did not move, but<br>
>>>>> it<br>
>>>>> would be really really really hard for the FCAL to make a significant<br>
>>>>> horizontal movement. I just isn't that mobile.<br>
>>>>><br>
>>>>> Matt<br>
>>>>><br>
>>>>><br>
>>>>>> On Feb 28, 2019, at 3:35 PM, Gan, Liping <ganl@uncw.edu> wrote:<br>
>>>>>><br>
>>>>>> Hi, Matt,<br>
>>>>>><br>
>>>>>> Do you know if FCAL position has been changed since 2015 survey?<br>
>>>>>><br>
>>>>>> Liping<br>
>>>>>><br>
>>>>>> From: GlueX-Collaboration <gluex-collaboration-bounces@jlab.org> On<br>
>>>>>> Behalf Of Simon Taylor<br>
>>>>>> Sent: Thursday, February 28, 2019 3:23 PM<br>
>>>>>> To: Ilya Larin <ilarin@jlab.org>; Shepherd, Matthew<br>
>>>>>> <mashephe@indiana.edu>; Ashot Gasparian <gasparan@jlab.org><br>
>>>>>> Cc: primexd@jlab.org; andrsmit@jlab.org; GlueX Collaboration<br>
>>>>>> <gluex-collaboration@jlab.org>; Mark Stevens <stevensm@jlab.org><br>
>>>>>> Subject: Re: [GlueX] Target installation plan<br>
>>>>>><br>
>>>>>> For what it's worth, according to the 2015 survey (I am not sure if<br>
>>>>>> the<br>
>>>>>> FCAL was resurveyed at a later date), the FCAL as a whole is off in<br>
>>>>>> x<br>
>>>>>> by<br>
>>>>>> about +5mm, but only a tiny amount off from zero in y.<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> In the attachment the highlighted numbers are z,x,y in meters.<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> Simon<br>
>>>>>><br>
>>>>>> From: GlueX-Collaboration <gluex-collaboration-bounces@jlab.org> on<br>
>>>>>> behalf of Ilya Larin <ilarin@jlab.org><br>
>>>>>> Sent: Thursday, February 28, 2019 2:58:38 PM<br>
>>>>>> To: Shepherd, Matthew; Ashot Gasparian<br>
>>>>>> Cc: primexd@jlab.org; andrsmit@jlab.org; GlueX Collaboration; Mark<br>
>>>>>> Stevens<br>
>>>>>> Subject: Re: [GlueX] Target installation plan<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> Hi Matt,<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> according to the pictures the square pipe is asymmetrical vs beam<br>
>>>>>> line<br>
>>>>>><br>
>>>>>> and is most likely causing the "shade" on ComCal face.<br>
>>>>>><br>
>>>>>> Wondering if FCAL is placed symmetrically vs beam,<br>
>>>>>><br>
>>>>>> that should mean that pipe doesn't exactly match FCAL hole.<br>
>>>>>><br>
>>>>>> The exact values from drawings would help and needed for MC<br>
>>>>>><br>
>>>>>> geometry db to get an exact acceptance.<br>
>>>>>><br>
>>>>>> If it is the case, that only mean we have to reduce ComCal<br>
>>>>>><br>
>>>>>> fiducial region for Compton events.<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> Thanks for pictures.<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> Ilya<br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>><br>
>>>>>> ÃÂzÃ',: GlueX-Collaboration<br>
>>>>>> <gluex-collaboration-bounces@jlab.org><br>
>>>>>> þÃ',<br>
>>>>>> øüõýø Shepherd, Matthew<br>
>>>>>> <mashephe@indiana.edu><br>
>>>>>> ÃÂzÃ',ÿÃ'?ðòûõýþ:<br>
>>>>>> 28 Ã'"õòÃ'?ðûÃ'ÂÂ<br>
>>>>>> 2019 ó. 12:49<br>
>>>>>> ÃÂsþüÃ'f: Ashot Gasparian<br>
>>>>>> ÃÂsþÿøÃ'ÂÂ: primexd@jlab.org;<br>
>>>>>> andrsmit@jlab.org; GlueX<br>
>>>>>> Collaboration;<br>
>>>>>> Mark Stevens<br>
>>>>>> âõüð: Re: [GlueX] Target installation<br>
>>>>>> plan<br>
>>>>>><br>
>>>>>><br>
>>>>>> Hi Ashot,<br>
>>>>>><br>
>>>>>>> On Feb 28, 2019, at 11:58 AM, gasparan@jlab.org wrote:<br>
>>>>>><br>
>>>>>>> Therefore, it would be extremely important to take pictures of the<br>
>>>>>> FCAL<br>
>>>>>>> insertion part and post on some place to see, before our meeting<br>
>>>>>>> this<br>
>>>>>>> evening.<br>
>>>>>><br>
>>>>>><br>
>>>>>> I've posted pictures of the FCAL insert here:<br>
>>>>>><br>
>>>>>> <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.proofpoint.com%2Fv2%2Furl%3Fu%3Dhttps-3A__logbooks.jlab.org_entry_3661206%26d%3DDwIFaQ%26c%3DimBPVzF25OnBgGmVOlcsiEgHoG1i6YHLR0Sj_gZ4adc%26r%3DsIYZlDyi2c__i74T9e_jiQlZA1kv9Tn6PdNHBK5I8-M%26m%3DmxMYBpb4tXg9KIFxMOcf4dLB9pVtNSFFMWGLYCNBDWA%26s%3DSApHZdtPEl9gtNCHr511mRyqv7X127F_IqfNUCRAKwE%26e%3D&data=02%7C01%7Cprimexd%40jlab.org%7Cf9422a10c93d47bce90708d69dc47cd0%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C1%7C636869864566954402&sdata=Tu2sZ8Qom4NqErikmhYjiu0N0reHvSA7W8FLzNwWuEo%3D&reserved=0" originalSrc="https://urldefense.proofpoint.com/v2/url?u=https-3A__logbooks.jlab.org_entry_3661206&d=DwIFaQ&c=imBPVzF25OnBgGmVOlcsiEgHoG1i6YHLR0Sj_gZ4adc&r=sIYZlDyi2c__i74T9e_jiQlZA1kv9Tn6PdNHBK5I8-M&m=mxMYBpb4tXg9KIFxMOcf4dLB9pVtNSFFMWGLYCNBDWA&s=SApHZdtPEl9gtNCHr511mRyqv7X127F_IqfNUCRAKwE&e=" shash="kph/nZT6ubMSZXonl3zPQVeU9JWKWSt4Hak9rLKYNKy12su2U/KzpF0D6ipvzCHtiHx+omi9Ohwbc+UyxieKTyrTIj+f0T+ojayPN55blEbj949z8gCY2cMEWQiKnLxft8kHzSVUpqA4bbZppDHygfLKEgne1G6KkPQm5NsX7BE=" id="LPlnk111665" class="OWAAutoLink" previewremoved="true">
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>>>>>><br>
>>>>>> It looked today exactly as it did 5+ years ago when these were<br>
>>>>>> taken.<br>
>>>>>> (I'm surprised you haven't taken a peek at it before as it defines<br>
>>>>>> the<br>
>>>>>> acceptance of your detector.)<br>
>>>>>><br>
>>>>>> The Plexiglas monitoring system is held in the groove on the<br>
>>>>>> upstream<br>
>>>>>> end. Anything of any density should be clear of the inner opening<br>
>>>>>> in<br>
>>>>>> the tube. From the darkroom all that is visible is what appears to<br>
>>>>>> be<br>
>>>>>> a<br>
>>>>>> thin tedlar cover on the upstream end. It is needed for a light<br>
>>>>>> seal<br>
>>>>>> or<br>
>>>>>> else there is light path from the hall into the darkroom via the<br>
>>>>>> beam<br>
>>>>>> pipe.<br>
>>>>>><br>
>>>>>> Matt<br>
>>>>>><br>
>>>>>> ---------------------------------------------------------------------<br>
>>>>>> Matthew Shepherd, Professor<br>
>>>>>> Department of Physics, Indiana University, Swain West 265<br>
>>>>>> 727 East Third Street, Bloomington, IN 47405<br>
>>>>>><br>
>>>>>> Office Phone: +1 812 856 5808<br>
><br>
><br>
<br>
<br>
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