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Dear Sangbaek and Whitney,</div>
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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.</div>
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So, the trigger 1 and trigger 2 (see below the extraction from your proposal) just will not work.</div>
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Let me know what you think.</div>
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Best regards,</div>
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Valery</div>
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Page 13:</div>
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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]. </div>
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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. </div>
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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</div>
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<span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><b>From:</b> clas_members <clas_members-bounces@jlab.org> on behalf of Sangbaek Lee via clas_members <clas_members@jlab.org><br>
<b>Sent:</b> Tuesday, April 30, 2024 08:39<br>
<b>To:</b> clas_members@jlab.org <clas_members@jlab.org><br>
<b>Cc:</b> Sangbaek Lee <sangbaek.lee@anl.gov><br>
<b>Subject:</b> [clas_members] [LOI to PAC 52] Measurement of the coherent J/psi Electroproduction off He-4 with the ALERT at 11 GeV</span>
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<div>Dear colleagues,</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>The letter can be found at the following link: <a href="https://urldefense.us/v3/__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__;!!G_uCfscf7eWS!cq0F4mbvGzEv5YLig16xzqXKop_s0fJ5-KculAIZcMWNsT7QfxChwVujJqSqchTvZDBqi_-9y4pp5GNbfcmfxx52NZMK7g$" id="OWAd33233f9-2b35-3664-1008-e1b5a5bcd227" class="OWAAutoLink" data-auth="NotApplicable">
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</a> </div>
<div>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.</div>
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<div>Please let us know if you would like to opt-in, by contacting me at <a href="mailto:sangbaek.lee@anl.gov" id="OWA2bb60ede-3a8c-c96c-1853-4506d979c241" class="OWAAutoLink">
sangbaek.lee@anl.gov</a> and Whitney Armstrong at <a href="mailto:warmstrong@anl.gov" id="OWA058cb725-22f7-a418-9a93-de40a2a30831" class="OWAAutoLink">
warmstrong@anl.gov</a>.</div>
<div>Also, if you have any comments or questions, please send them to me and to Whitney Armstrong.</div>
<div>The letter will be submitted to the PAC 52 by 9 a.m. JLab time on Wednesday, 5/1/2024.</div>
<div><br>
</div>
<div>Sincerely,</div>
<div>Sangbaek and Whitney</div>
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