[Primexd] [GlueX] Target installation plan

Thu Feb 28 16:34:11 EST 2019

Hi Matt,

Here is a link to the meeting in case you cannot be in the counting house at 5pm:

Bluejeans link: https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjlab.bluejeans.com%2F7572695553&data=02%7C01%7Cprimexd%40jlab.org%7Cf9422a10c93d47bce90708d69dc47cd0%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C1%7C636869864566844330&sdata=vUxlx4AiKb9pS33kHTlTbmsLeW%2BAPVRfZnwVex%2FjdEo%3D&reserved=0

<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjlab.bluejeans.com%2F7572695553&data=02%7C01%7Cprimexd%40jlab.org%7Cf9422a10c93d47bce90708d69dc47cd0%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C1%7C636869864566844330&sdata=vUxlx4AiKb9pS33kHTlTbmsLeW%2BAPVRfZnwVex%2FjdEo%3D&reserved=0>

Best,

- Drew

________________________________
From: Primexd <primexd-bounces at jlab.org> on behalf of gasparan at jlab.org <gasparan at jlab.org>
Sent: Thursday, February 28, 2019 4:19:16 PM
To: Shepherd, Matthew
Cc: primexd at jlab.org; Simon Taylor; andrsmit at jlab.org; Mark Stevens
Subject: Re: [Primexd] [GlueX] Target installation plan

  Matt,
 Please try to be at the 5 pm meeting and we discuss them.

 If the FCAL is shadowing the CCAL then no software alignment
 will give us a reasonable statistics.

 Thanks,
 Ashot

> Ashot,
>
>> What we have is a Large asymetry.
>> I think we have to understand how to solve it to go forward with the
>> data taking process.
>
>
> You solve the asymmetry by aligning your detector not with the beam line
> as you have done now but instead the FCAL beam hole.
>
> Unfortunately, doing so means that you significantly change the acceptance
> of your detector.  And because of that you may want to reconsider taking
> the data you have collected already.
>
> The cause seems pretty clear -- you just need a strategy that let's you
> make the measurement with acceptable systematic uncertainties.
>
> I suspect you'll see the same effect in your December data also.
>
> Matt
>
>
>> On Feb 28, 2019, at 4:06 PM, gasparan at jlab.org wrote:
>>
>>
>> Matt, before I go through your email and try to discuss, one thing
>> we have to take care of is the real data.
>> We probably agree that in order to have better and usable data the
>> acceptances need to be symmetrical. What we have is a Large asymetry.
>> I think we have to understand how to solve it to go forward with the
>> data taking process.
>>
>> let's discuss this in today's meeting.
>>
>> Thanks,
>> Ashot
>>
>>>
>>> Ashot,
>>>
>>> I don't think a survey of the beam line is needed.  I think you just
>>> need
>>> to use the existing survey.
>>>
>>> I realized that it completely explains your asymmetry.
>>>
>>> As Justin noted, the Compton image on the CCAL is exactly as you
>>> predict,
>>> just shifted by 2 cm.  What I neglected in my previous message is that
>>> if
>>> you make a shift of CCAL by 1 cm you effectively shift the image by 2
>>> cm.
>>> In your reconstruction, shifting CCAL to +x by 1 cm will make the
>>> Compton
>>> occupancy go from -9 cm to +9 cm on the CCAL (instead of -8 cm to + 10
>>> cm).
>>>
>>> Now, if you need to shift CCAL by 1 cm, it means that, because of the
>>> lever arm, the FCAL is shifted about 5 mm to +X.  This is exactly as
>>> reported by Simon.  And there is no vertical offset, also as reported
>>> by
>>> Simon.
>>>
>>> Seems the conclusion is straightforward:
>>>
>>> Your asymmetry of Compton events is not related to excess material in
>>> the
>>> beam line, or bugs in reconstruction, it is byproduct of the already
>>> known
>>> alignment of the FCAL with respect to the beam line.  Again, working
>>> with
>>> simulation done in the Hall D framework will demonstrate these effects.
>>>
>>> Seems like you have two choices now:
>>>
>>> * Align CCAL not on beam center but on FCAL hole center.  But then you
>>> may
>>> want to retake Be data.
>>> * Live with existing alignment and explore systematics.
>>>
>>> Matt
>>>
>>>
>>>> On Feb 28, 2019, at 3:48 PM, gasparan at jlab.org wrote:
>>>>
>>>>
>>>> Dear Matt and All,
>>>>
>>>> At this stage it is clear that we should survey entire beam line,
>>>> for sure including the FCAL (not only CCAL).
>>>>
>>>> The question is what to do next.
>>>>
>>>> Ashot
>>>>
>>>>
>>>>>
>>>>> Liping,
>>>>>
>>>>> Without survey I cannot definitively assert that it did not move, but
>>>>> it
>>>>> would be really really really hard for the FCAL to make a significant
>>>>> horizontal movement.  I just isn't that mobile.
>>>>>
>>>>> Matt
>>>>>
>>>>>
>>>>>> On Feb 28, 2019, at 3:35 PM, Gan, Liping <ganl at uncw.edu> wrote:
>>>>>>
>>>>>> Hi, Matt,
>>>>>>
>>>>>> Do you know if FCAL position has been changed since 2015 survey?
>>>>>>
>>>>>> Liping
>>>>>>
>>>>>> From: GlueX-Collaboration <gluex-collaboration-bounces at jlab.org> On
>>>>>> Behalf Of Simon Taylor
>>>>>> Sent: Thursday, February 28, 2019 3:23 PM
>>>>>> To: Ilya Larin <ilarin at jlab.org>; Shepherd, Matthew
>>>>>> <mashephe at indiana.edu>; Ashot Gasparian <gasparan at jlab.org>
>>>>>> Cc: primexd at jlab.org; andrsmit at jlab.org; GlueX Collaboration
>>>>>> <gluex-collaboration at jlab.org>; Mark Stevens <stevensm at jlab.org>
>>>>>> Subject: Re: [GlueX] Target installation plan
>>>>>>
>>>>>> For what it's worth, according to the 2015 survey (I am not sure if
>>>>>> the
>>>>>> FCAL was resurveyed at a later date), the FCAL as a whole is off in
>>>>>> x
>>>>>> by
>>>>>> about +5mm, but only a tiny amount off from zero in y.
>>>>>>
>>>>>>
>>>>>>
>>>>>> In the attachment the highlighted numbers are z,x,y in meters.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Simon
>>>>>>
>>>>>> From: GlueX-Collaboration <gluex-collaboration-bounces at jlab.org> on
>>>>>> behalf of Ilya Larin <ilarin at jlab.org>
>>>>>> Sent: Thursday, February 28, 2019 2:58:38 PM
>>>>>> To: Shepherd, Matthew; Ashot Gasparian
>>>>>> Cc: primexd at jlab.org; andrsmit at jlab.org; GlueX Collaboration; Mark
>>>>>> Stevens
>>>>>> Subject: Re: [GlueX] Target installation plan
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi Matt,
>>>>>>
>>>>>>
>>>>>>
>>>>>> according to the pictures the square pipe is asymmetrical vs beam
>>>>>> line
>>>>>>
>>>>>> and is most likely causing the "shade" on ComCal face.
>>>>>>
>>>>>> Wondering if  FCAL is placed symmetrically vs beam,
>>>>>>
>>>>>> that should mean that pipe doesn't exactly match FCAL hole.
>>>>>>
>>>>>> The exact values from drawings would help and needed for MC
>>>>>>
>>>>>> geometry db to get an exact acceptance.
>>>>>>
>>>>>> If it is the case, that only mean we have to reduce ComCal
>>>>>>
>>>>>> fiducial region for Compton events.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Thanks for pictures.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Ilya
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ÃƒÂzÃƒ',: GlueX-Collaboration
>>>>>> <gluex-collaboration-bounces at jlab.org>
>>>>>> ÃƒÂÃ‚Â¾Ãƒ',
>>>>>> ÃƒÂÃ‚Â¸ÃƒÂÃ‚Â¼ÃƒÂÃ‚ÂµÃƒÂÃ‚Â½ÃƒÂÃ‚Â¸ Shepherd, Matthew
>>>>>> <mashephe at indiana.edu>
>>>>>> ÃƒÂzÃƒ',ÃƒÂÃ‚Â¿Ãƒ'?ÃƒÂÃ‚Â°ÃƒÂÃ‚Â²ÃƒÂÃ‚Â»ÃƒÂÃ‚ÂµÃƒÂÃ‚Â½ÃƒÂÃ‚Â¾:
>>>>>> 28 Ãƒ'"ÃƒÂÃ‚ÂµÃƒÂÃ‚Â²Ãƒ'?ÃƒÂÃ‚Â°ÃƒÂÃ‚Â»Ãƒ'Ã‚Â
>>>>>> 2019 ÃƒÂÃ‚Â³. 12:49
>>>>>> ÃƒÂsÃƒÂÃ‚Â¾ÃƒÂÃ‚Â¼Ãƒ'f: Ashot Gasparian
>>>>>> ÃƒÂsÃƒÂÃ‚Â¾ÃƒÂÃ‚Â¿ÃƒÂÃ‚Â¸Ãƒ'Ã‚Â: primexd at jlab.org;
>>>>>> andrsmit at jlab.org; GlueX
>>>>>> Collaboration;
>>>>>> Mark Stevens
>>>>>> ÃƒÂÃ‚Â¢ÃƒÂÃ‚ÂµÃƒÂÃ‚Â¼ÃƒÂÃ‚Â°: Re: [GlueX] Target installation
>>>>>> plan
>>>>>>
>>>>>>
>>>>>> Hi Ashot,
>>>>>>
>>>>>>> On Feb 28, 2019, at 11:58 AM, gasparan at jlab.org wrote:
>>>>>>
>>>>>>> Therefore, it would be extremely important to take pictures of the
>>>>>> FCAL
>>>>>>> insertion part and post on some place to see, before our meeting
>>>>>>> this
>>>>>>> evening.
>>>>>>
>>>>>>
>>>>>> I've posted pictures of the FCAL insert here:
>>>>>>
>>>>>> 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&data=02%7C01%7Cprimexd%40jlab.org%7Cf9422a10c93d47bce90708d69dc47cd0%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636869864566844330&sdata=y3j1dSNiseXJPiYJrWcD9NPrTCvYK%2Bg3uI0E5JUJK5I%3D&reserved=0=
>>>>>>
>>>>>> It looked today exactly as it did 5+ years ago when these were
>>>>>> taken.
>>>>>> (I'm surprised you haven't taken a peek at it before as it defines
>>>>>> the
>>>>>> acceptance of your detector.)
>>>>>>
>>>>>> The Plexiglas monitoring system is held in the groove on the
>>>>>> upstream
>>>>>> end.  Anything of any density should be clear of the inner opening
>>>>>> in
>>>>>> the tube.  From the darkroom all that is visible is what appears to
>>>>>> be
>>>>>> a
>>>>>> thin tedlar cover on the upstream end.  It is needed for a light
>>>>>> seal
>>>>>> or
>>>>>> else there is light path from the hall into the darkroom via the
>>>>>> beam
>>>>>> pipe.
>>>>>>
>>>>>> Matt
>>>>>>
>>>>>> ---------------------------------------------------------------------
>>>>>> Matthew Shepherd, Professor
>>>>>> Department of Physics, Indiana University, Swain West 265
>>>>>> 727 East Third Street, Bloomington, IN 47405
>>>>>>
>>>>>> Office Phone:  +1 812 856 5808
>
>

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