[Clas12_verystrange] Beam Energy Requirements in Hall B

Wed Jul 31 16:31:45 EDT 2024

Dear Eugene and all

It was not intended that extensive simulations should be done. As Eugene wrote, estimates are fine.

In terms of statistics, we should not look into effects of +/- 10 percent, which is below the fluctuations in the assignment of 2 calendar days per 1 PAC day. As an example, if an experiment will need 3 calendar days per 1 PAC day when running at a lower beam energy, then this is notable.

Best,
Patrick

________________________________
From: Clas12_verystrange <clas12_verystrange-bounces at jlab.org> on behalf of Eugene Pasyuk via Clas12_verystrange <clas12_verystrange at jlab.org>
Sent: Wednesday, July 31, 2024 16:20
To: clas12 verystrange <clas12_verystrange at jlab.org>
Subject: [Clas12_verystrange] FW: Beam Energy Requirements in Hall B

Hello strangers,

When we wrote our proposals over a decade ago, we assumed an electron beam energy of 11 GeV.

We were asked to evaluate the impact on the expected results if we ran at lower energy and the minimum acceptable beam energy. See Latifa’s message below. In the first installation of RGA, we were running at ~10.6 GeV. Some of RGB was even lower, ~10.4 GeV.

Regarding the strongness program, the higher energy means higher statistics because the incident energy extends farther above thresholds, and we get more virtual photon flux above thresholds, which translates to higher reaction yield. We should try to quantify the impact, for instance, assuming beam energy 10.4 vs 11 GeV. If this impact is significant, we may request additional beam time to compensate for the losses due to running at lower energy. Any volunteers to make an estimate?

Please think about it, send your thoughts and we will discuss this at our meeting next week.

Cheers,

-Eugene

From: Latifa Elouadrhiri <latifa at jlab.org>
Date: Wednesday, July 31, 2024 at 09:53
To: Rafayel Paremuzyan <rafopar at jlab.org>, Francois-Xavier Girod-Gard <fxgirod at jlab.org>, Harut Avagyan <avakian at jlab.org>, Ralf Gothe <rwgothe at gmail.com>, Derek.Glazier at glasgow.ac.uk <derek.glazier at glasgow.ac.uk>, Eugene Pasyuk <pasyuk at jlab.org>
Cc: Stepan Stepanyan <stepanya at jlab.org>, Volker Burkert <burkert at jlab.org>, Latifa Elouadrhiri <latifa at jlab.org>
Subject: Fw: Beam Energy Requirements in Hall B

Dear all,

As we discussed this morning, please see Patrick's email below and provide your answers to the questions regarding your physics experiments and send them to me by Monday, August 12. I will compile everything for discussion on Wednesday, August 16, in order to finalize the document and send it to Patrick.

Volker and Stepan, if you could please send me the comments you made this morning to include in the document as a separate note that would be great.

Let me know if you have any questions.

Best regards,

Latifa

________________________________

From: Patrick Achenbach <patricka at jlab.org>
Sent: Tuesday, July 23, 2024 5:47 PM
To: Latifa Elouadrhiri <latifa at jlab.org>; Silvia Niccolai <silvia.niccolai at ijclab.in2p3.fr>; Sebastian E. Kuhn <skuhn at odu.edu>; Raphael Dupre <raphael.dupre at ijclab.in2p3.fr>; Hayk Hakobyan <hayk.hakobyan at usm.cl>; Ilya Larin <ilarin at jlab.org>; mcontalb at fe.infn.it <mcontalb at fe.infn.it>; William Brooks <william.brooks at usm.cl>; Richard G Milner <milner at mit.edu>
Cc: Stepan Stepanyan <stepanya at jlab.org>
Subject: Beam Energy Requirements in Hall B

Dear contact persons of '11-GeV runs' in Hall-B,

Earlier this year, DOE has performed an Operations Review which was concluded with a list of comments and recommendations. One particular recommendation is to... "Develop a beam energy requirement document for the approved experiments in the experimental halls, complete with physics justifications. This document must be distinctly separate from issues pertaining to reliability."

Physics division will compile, for each experiment still to run, (a) Proposed Energies, (b) Minimum Acceptable Maximum Energy if 12 GeV was proposed, (c) Science Impact of difference from 12 GeV, and (d) any potential mitigation such as run longer.

The focus of this recommendation is a review/justification for a 12-GeV CEBAF beam (equiv. to 11 GeV delivered to Hall B) as compared to a beam with some 100s MeV less energy.

Can you please give me input to the requested table entries (a) to (d)? Feel free to justify running at 11 GeV for Hall B with some extra narrative if the table is not sufficient. I believe, we can give common numbers for experiments in run groups for which the science impact and the potential mitigation is similar. However, I don't think that we can combine all experiments from a run group.

Let me remind you, the scheduled beam energy for the next run is 1060 MeV per linac, equiv. to 10.70 GeV in Hall B. Plans are in place to increase this to 1090 MeV, equiv. to 11 GeV in Hall B for the FY26, but not at all cost.

Physics division is not moving quickly on this, so a reasonable target to have all information compiled is August 20, 2024.

Best regards,

Patrick

________________________________
From: Clas12_verystrange <clas12_verystrange-bounces at jlab.org> on behalf of Eugene Pasyuk via Clas12_verystrange <clas12_verystrange at jlab.org>
Sent: Wednesday, July 31, 2024 16:20
To: clas12 verystrange <clas12_verystrange at jlab.org>
Subject: [Clas12_verystrange] FW: Beam Energy Requirements in Hall B

Hello strangers,

When we wrote our proposals over a decade ago, we assumed an electron beam energy of 11 GeV.

We were asked to evaluate the impact on the expected results if we ran at lower energy and the minimum acceptable beam energy. See Latifa’s message below. In the first installation of RGA, we were running at ~10.6 GeV. Some of RGB was even lower, ~10.4 GeV.

Regarding the strongness program, the higher energy means higher statistics because the incident energy extends farther above thresholds, and we get more virtual photon flux above thresholds, which translates to higher reaction yield. We should try to quantify the impact, for instance, assuming beam energy 10.4 vs 11 GeV. If this impact is significant, we may request additional beam time to compensate for the losses due to running at lower energy. Any volunteers to make an estimate?

Please think about it, send your thoughts and we will discuss this at our meeting next week.

Cheers,

-Eugene

From: Latifa Elouadrhiri <latifa at jlab.org>
Date: Wednesday, July 31, 2024 at 09:53
To: Rafayel Paremuzyan <rafopar at jlab.org>, Francois-Xavier Girod-Gard <fxgirod at jlab.org>, Harut Avagyan <avakian at jlab.org>, Ralf Gothe <rwgothe at gmail.com>, Derek.Glazier at glasgow.ac.uk <derek.glazier at glasgow.ac.uk>, Eugene Pasyuk <pasyuk at jlab.org>
Cc: Stepan Stepanyan <stepanya at jlab.org>, Volker Burkert <burkert at jlab.org>, Latifa Elouadrhiri <latifa at jlab.org>
Subject: Fw: Beam Energy Requirements in Hall B

Dear all,

As we discussed this morning, please see Patrick's email below and provide your answers to the questions regarding your physics experiments and send them to me by Monday, August 12. I will compile everything for discussion on Wednesday, August 16, in order to finalize the document and send it to Patrick.

Volker and Stepan, if you could please send me the comments you made this morning to include in the document as a separate note that would be great.

Let me know if you have any questions.

Best regards,

Latifa

________________________________

From: Patrick Achenbach <patricka at jlab.org>
Sent: Tuesday, July 23, 2024 5:47 PM
To: Latifa Elouadrhiri <latifa at jlab.org>; Silvia Niccolai <silvia.niccolai at ijclab.in2p3.fr>; Sebastian E. Kuhn <skuhn at odu.edu>; Raphael Dupre <raphael.dupre at ijclab.in2p3.fr>; Hayk Hakobyan <hayk.hakobyan at usm.cl>; Ilya Larin <ilarin at jlab.org>; mcontalb at fe.infn.it <mcontalb at fe.infn.it>; William Brooks <william.brooks at usm.cl>; Richard G Milner <milner at mit.edu>
Cc: Stepan Stepanyan <stepanya at jlab.org>
Subject: Beam Energy Requirements in Hall B

Dear contact persons of '11-GeV runs' in Hall-B,

Earlier this year, DOE has performed an Operations Review which was concluded with a list of comments and recommendations. One particular recommendation is to... "Develop a beam energy requirement document for the approved experiments in the experimental halls, complete with physics justifications. This document must be distinctly separate from issues pertaining to reliability."

Physics division will compile, for each experiment still to run, (a) Proposed Energies, (b) Minimum Acceptable Maximum Energy if 12 GeV was proposed, (c) Science Impact of difference from 12 GeV, and (d) any potential mitigation such as run longer.

The focus of this recommendation is a review/justification for a 12-GeV CEBAF beam (equiv. to 11 GeV delivered to Hall B) as compared to a beam with some 100s MeV less energy.

Can you please give me input to the requested table entries (a) to (d)? Feel free to justify running at 11 GeV for Hall B with some extra narrative if the table is not sufficient. I believe, we can give common numbers for experiments in run groups for which the science impact and the potential mitigation is similar. However, I don't think that we can combine all experiments from a run group.

Let me remind you, the scheduled beam energy for the next run is 1060 MeV per linac, equiv. to 10.70 GeV in Hall B. Plans are in place to increase this to 1090 MeV, equiv. to 11 GeV in Hall B for the FY26, but not at all cost.

Physics division is not moving quickly on this, so a reasonable target to have all information compiled is August 20, 2024.

Best regards,

Patrick
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