[Halld-tagger] [EXTERNAL] Re: DBeamPhoton tests

[Alexander Austregesilo]

Dear Richard,

My first item, the single bin near 9.1 which loses 15%, is in the 
*hodoscope* region, that is why it only shows up in Sean's branch 
(ver10, red). The question was more directed towards Sasha or Sean.

Are you still planning to submit a pull request today?

Cheers,

Alex


On 4/24/2020 1:15 PM, Richard Jones wrote:
> Alexander, my response to your questions. -Richard
>
>     Comparing the two versions with and without the requirement of ADC/TDC
>     matching for the hodoscope, I only see a loss of events below 1% in
>     almost the full energy range. There is only one 100MeV-wide bin near
>     9.1GeV, where the loss is about 15%. Could this be a sign of a
>     broken or
>     miscalibrated TDC?
>
>
> No, the DAQ was working ok in that sector. The loss of 15% is pretty 
> much uniform across the entire TAGM. The reason the ratio looks like 1 
> in the low-energy end is because the missed tags are missing from both 
> the numerator (tdc*adc) and denominator (adc) in that region, so the 
> ratio looks close to 1. I will present my analysis of these data at 
> the beamline meeting next Tuesday.
>
>      Once the thresholds were fixed in run 71724, the loss goes down
>     to 10%
>     in the higher-energy part of the microscope, while it completely
>     recovers for the low-energy part. What is the reason for this
>     discrepancy? New vs old fibers?
>
>
> Basically the ratio is close to 1 in the low-energy end of the TAGM 
> because the low-amplitude pulses are missed by both the adc and tdc. 
> What really surprised me is the additional tags that are recovered at 
> the high-energy end where the new fibers are: by lowering the adc 
> threshold way down, we are able to see an additional 15% of tags in 
> the adc over what is seen by the tdc which just counts on the primary 
> MIP peak. I believe that this 15% are coming from electrons that 
> passed through the cladding of the fiber, instead of the core. 
> Originally I assumed that light produced in the cladding would be 
> totally lost because it is outside the total-internal-reflection 
> capture cone of the fiber. Now I see that this assumption was wrong! 
> Nevertheless, there is probably not enough light from these pulses to 
> make good tags.
>
> Let's discuss the "15% problem" at the beamline meeting next week.
>
> On Fri, Apr 24, 2020 at 11:46 AM Alexander Austregesilo 
> <aaustreg at jlab.org <mailto:aaustreg at jlab.org>> wrote:
>
>     *Message sent from a system outside of UConn.*
>
>
>     Hi,
>
>     I looked at the accidental corrected rho yields as a function of
>     energy
>     for the three test runs. You can see the plots on this wiki page:
>
>     https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhalldweb.jlab.org%2Fwiki-private%2Findex.php%2F2020_TagM_Threshold_Test&data=02%7C01%7Crichard.t.jones%40uconn.edu%7Ca352d79c11974c79fea808d7e866a12e%7C17f1a87e2a254eaab9df9d439034b080%7C0%7C0%7C637233399810094785&sdata=4zYaxV2ZzXphRsiaR5eFzgX3ebxm%2BHN7owoyTIl%2F1lA%3D&reserved=0
>     <https://urldefense.proofpoint.com/v2/url?u=https-3A__nam10.safelinks.protection.outlook.com_-3Furl-3Dhttps-253A-252F-252Fhalldweb.jlab.org-252Fwiki-2Dprivate-252Findex.php-252F2020-5FTagM-5FThreshold-5FTest-26amp-3Bdata-3D02-257C01-257Crichard.t.jones-2540uconn.edu-257Ca352d79c11974c79fea808d7e866a12e-257C17f1a87e2a254eaab9df9d439034b080-257C0-257C0-257C637233399810094785-26amp-3Bsdata-3D4zYaxV2ZzXphRsiaR5eFzgX3ebxm-252BHN7owoyTIl-252F1lA-253D-26amp-3Breserved-3D0&d=DwMFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=9LGv0gfS3B8uAbsk8r_cEX_4GVRxd2wkj-RJy5MLidg&m=vEgBctGyqGiFqUYKDPZj5ruXlVsTBzGsfO06rswPQFA&s=6rlUaB4IB4F1ys1ZFI1UPihxKMvDbR2wbmt59FSvyMA&e=>
>
>     Comparing the two versions with and without the requirement of ADC/TDC
>     matching for the hodoscope, I only see a loss of events below 1% in
>     almost the full energy range. There is only one 100MeV-wide bin near
>     9.1GeV, where the loss is about 15%. Could this be a sign of a
>     broken or
>     miscalibrated TDC?
>
>     For the 2 runs before the adjustment of the microscope thresholds, the
>     loss of rho events with tagged beam photons is close to 30% as
>     expected.
>     Once the thresholds were fixed in run 71724, the loss goes down to 10%
>     in the higher-energy part of the microscope, while it completely
>     recovers for the low-energy part. What is the reason for this
>     discrepancy? New vs old fibers?
>
>     Best regards,
>
>     Alex
>
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