[clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV

Tue Apr 30 16:10:12 EDT 2024

Dear J/Psi enthousiasts!
 The  calculation by Acker et al does not include the "life saving" solenoid magnet.
The attached series of graphs based on simulations from Alex Vlassov (shot from by iphone from some paper copies)  illustrates the effect of the solenoid magnet and the Moller cone. For comparison the first graph is taken with 10^33 Lumi w/o magnetic field, the second (top) with full luminosity (w/o magnetic field), the third with full luminosity and magnetic field, the fourth with full luminosity and magnetic field + a Moller shielding pipe. All background events are in the pipe.
Of course, the FT calorimetry was not installed for this simulation, but it will affect the resulst by a fcator maximum.

So, relax, your 120MHz trigger rate will be down by a huge factor ......      In fact Valery should have those data already .

Cheers,
Volker

________________________________
From: clas_members <clas_members-bounces at jlab.org> on behalf of Valery Kubarovsky via clas_members <clas_members at jlab.org>
Sent: Tuesday, April 30, 2024 1:23 PM
To: Armstrong, Whitney R. <warmstrong at anl.gov>; clas_members at jlab.org <clas_members at jlab.org>; Sangbaek Lee <sangbaek at jlab.org>
Cc: Lee, Sangbaek <sangbaek.lee at anl.gov>
Subject: Re: [clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV

Ok, I get it. Thank you for the clarification.
I will be happy to join the proposal.
Valery

________________________________
From: Armstrong, Whitney R. <warmstrong at anl.gov>
Sent: Tuesday, April 30, 2024 12:44
To: Valery Kubarovsky <vpk at jlab.org>; clas_members at jlab.org <clas_members at jlab.org>; Sangbaek Lee <sangbaek at jlab.org>
Cc: Lee, Sangbaek <sangbaek.lee at anl.gov>
Subject: [EXTERNAL] Re: [clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV

This is correct for Run Group L. The trigger reconfiguration is a notable difference for this LOI compared to Run Group L.

That is, a full proposal will request new beam time with a different trigger configuration.

Please let me know if this is not clear or if you have any other concerns about the trigger or daq.

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From: clas_members <clas_members-bounces at jlab.org> on behalf of Valery Kubarovsky via clas_members <clas_members at jlab.org>
Sent: Tuesday, April 30, 2024 11:35:19 AM
To: clas_members at jlab.org <clas_members at jlab.org>; Sangbaek Lee <sangbaek at jlab.org>
Cc: Lee, Sangbaek <sangbaek.lee at anl.gov>
Subject: Re: [clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV

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Dear Sangbaek and Whitney,
I have some concerns about proposed trigger for the ALERT experiment. As for my knowledge, we don't expect any trigger from the ALERT detector to be incorporated to the CLAS12 trigger system.
So, the trigger 1 and trigger 2 (see below the extraction from your proposal) just will not work.
Let me know what you think.
Best regards,
Valery

Page 13:
At the nominal CLAS12 luminosity, O(1035 cm−2s−1), the forward tagger subsystem trigger rate is NFT = 120 MHz [49]. Clearly a trigger that solely relies on FT cannot be handled by the current CLAS12 DAQ without significant inefficiency– noting the nominal DAQ trigger rate is 20 kHz [50].
The first trigger (Trigger 1) is focused on the scattered electron detection and 4He detection in ALERT. The accidental coincidence event rate of FT and ALERT can be estimated as Ncoin = NFTNALERTτ, where τ is the coincidence time window. The estimated background rates are shown in Fig. 2.5. We conservatively estimate NALERT as 1 kHz over the momentum range 0.3 MeV/c < p < 1.1 GeV/c. The coincidence time window is conservatively set to 100 ns, which is on the order of the AHDC drift time [51]. The total coincidence trigger rate is then estimated to be roughly 12 kHz.
The second trigger (Trigger 2) configuration is based on the coincidence of ALERT and FD. The FD trigger condition is either on the scattered electron, or dilepton pair from J/ψ. Both triggers are operating for the existing experiments [50]. Target and Beam Configuration

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From: clas_members <clas_members-bounces at jlab.org> on behalf of Sangbaek Lee via clas_members <clas_members at jlab.org>
Sent: Tuesday, April 30, 2024 08:39
To: clas_members at jlab.org <clas_members at jlab.org>
Cc: Sangbaek Lee <sangbaek.lee at anl.gov>
Subject: [clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV

Dear colleagues,

I am pleased to circulate this PAC 52 Letter of Intent (LOI) "Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV" after review.

The letter can be found at the following link: https://www.jlab.org/Hall-B/shifts/admin/paper_reviews/2024/Coherent_jpsi_electroproduction_pac52_without_beamtime_estimate.pdf-4616787-2024-04-29-v4.pdf<https://urldefense.proofpoint.com/v2/url?u=https-3A__urldefense.us_v3_-5F-5Fhttps-3A__www.jlab.org_Hall-2DB_shifts_admin_paper-5Freviews_2024_Coherent-5Fjpsi-5Felectroproduction-5Fpac52-5Fwithout-5Fbeamtime-5Festimate.pdf-2D4616787-2D2024-2D04-2D29-2Dv4.pdf-5F-5F-3B-21-21G-5FuCfscf7eWS-21cq0F4mbvGzEv5YLig16xzqXKop-5Fs0fJ5-2DKculAIZcMWNsT7QfxChwVujJqSqchTvZDBqi-5F-2D9y4pp5GNbfcmfxx52NZMK7g-24&d=DwMGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=i-zbrSHrZkrcFN1WPMTnag&m=JknL4WqKV76xcof7jycVEQ4WlNS9UsluPAWasIJOyZiQnedNiF62uZXMZFuixsiO&s=tjpsMtGkgO0rcbuFPzOYzzgATUGepYu-R4MfV1gVQbw&e=>
We aim to measure the location of a diffraction minimum in the differential cross section to compare the gluonic gravitational form factor and charge form factor. The secondary goal is to extract the gluonic gravitational form factors of He-4.

Please let us know if you would like to opt-in, by contacting me at sangbaek.lee at anl.gov<mailto:sangbaek.lee at anl.gov> and Whitney Armstrong at warmstrong at anl.gov<mailto:warmstrong at anl.gov>.
Also, if you have any comments or questions, please send them to me and to Whitney Armstrong.
The letter will be submitted to the PAC 52 by 9 a.m. JLab time on Wednesday, 5/1/2024.

Sincerely,
Sangbaek and Whitney
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