[PRad] [EXTERNAL] Re: Fwd: paper on mainz measurements using gas jet target

[Haiyan Gao]

Dear Patrick:
Thank you for the detailed information which is very helpful. As I mentioned, I only looked at the paper very quickly and was not aware of its existence prior to Ashot sharing the information about this publication.

Best, Haiyan


***********************************************

Haiyan Gao

Robert C. Richardson Distinguished Professor of Physics

Department of Physics

French Family Science Center 2313

Duke University

Durham, NC 27708

Email: hgao at duke.edu<mailto:hgao at duke.edu>

Phone: 919-660-2622

https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tunl.duke.edu_-7Emep&d=DwIGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=_PD6jg7C_oeff7rIdbHlCiFUHnPsfGvnAy-_snUFmwGcayMCelbsEH5UhHUvMceO&s=BF0lNqSv6KSRCAPhcQTJYB6xUePf6YxwZX1LCBZdFnU&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tunl.duke.edu_-7Emep&d=DwIGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=_PD6jg7C_oeff7rIdbHlCiFUHnPsfGvnAy-_snUFmwGcayMCelbsEH5UhHUvMceO&s=BF0lNqSv6KSRCAPhcQTJYB6xUePf6YxwZX1LCBZdFnU&e= >

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From: Patrick Achenbach <patricka at jlab.org>
Date: Saturday, November 22, 2025 at 3:13 AM
To: gasparan <gasparan at jlab.org>, PRad mail group <prad at jlab.org>, Haiyan Gao <haiyan.gao at duke.edu>
Subject: Re: [PRad] [EXTERNAL] Re: Fwd: paper on mainz measurements using gas jet target

Dear all,

I don't think that anyone interpreted the gas-jet data points as a confirmation (or refutation) of the PRad-I data and I hope that I can explain the situation.

With only a handful Q2 points and a floating normalization, the gas-jet experiment was not able to differentiate between the MAMI 2010 data set and the PRad-I data points. Figure 8 shows the gas-jet data points fitted with the PRad-I Rationale(1,1) parametrization in blue and alternatively fitted with the Mainz’s polynomial parametrization in red. Both alternatives are equally possible given the limited statistics. The reduced chi-square value is not a good discriminator for this very small number of degrees of freedom. It was also not possible to determine a statistically meaningful slope parameter in this Q2 range, and the paper is not reporting its value.

If you carefully read Section IV. A. of the paper, you will realize that the experiment was mainly focused on commissioning the new gas-jet target and its collimator and veto systems. You can consider this paper as a demonstration that the new system has been working successfully and that a meaningful form factor extraction can be done if enough statistics were collected and enough kinematic points were covered. This is planned for Summer 2026.

While statistics is not an issue in typical forward-angle elastic scattering kinematics with a liquid hydrogen target, the gas-jet target provided a limited luminosity and a limited jet over residual gas ratio. There is a new target operation mode that, in the detector lab, proofed to be very promising. The 2026 beamtime will try to implement this new mode.

Best,
Patrick

________________________________
From: PRad <prad-bounces at jlab.org> on behalf of Haiyan Gao via PRad <prad at jlab.org>
Sent: Friday, November 21, 2025 14:07
To: gasparan <gasparan at jlab.org>; PRad mail group <prad at jlab.org>
Subject: [PRad] [EXTERNAL] Re: Fwd: paper on mainz measurements using gas jet target

Hello Ashot:
Somehow even Jan Bernauer did not mention much about this work. I just took a quick look, and their results are in better agreement with the PRad fit.

Best, Haiyan


***********************************************

Haiyan Gao

Robert C. Richardson Distinguished Professor of Physics

Department of Physics

French Family Science Center 2313

Duke University

Durham, NC 27708

Email: hgao at duke.edu<mailto:hgao at duke.edu>

Phone: 919-660-2622

https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tunl.duke.edu_-7Emep&d=DwIGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=_PD6jg7C_oeff7rIdbHlCiFUHnPsfGvnAy-_snUFmwGcayMCelbsEH5UhHUvMceO&s=BF0lNqSv6KSRCAPhcQTJYB6xUePf6YxwZX1LCBZdFnU&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tunl.duke.edu_-7Emep&d=DwMGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=oosjxsZaN9Gcq4x9-K3gOa-hx4fhePCHwCzeuoeHV5x4azGRA7fLcgexBIhP2s9d&s=fuOKdNiFdIMdHz3lQ9bJBCTz-h2NPquLrXw0U_A4d4I&e=>

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From: PRad <prad-bounces at jlab.org> on behalf of gasparan via PRad <prad at jlab.org>
Date: Friday, November 21, 2025 at 2:01 PM
To: PRad mail group <prad at jlab.org>
Subject: [PRad] Fwd: paper on mainz measurements using gas jet target


  Please check this publication pointed out by Adam (a CLAS collaborator)
related the
  new form factor date by Minz since 2022.

  Ashot


-------- Original Message --------
Subject: paper on mainz measurements using gas jet target
Date: 2025-11-21 12:40
 From: ajhobart <ajhobart at jlab.org>
To: gasparan at jlab.org

Dear Ashot,

The paper I was speaking about is:

https://urldefense.proofpoint.com/v2/url?u=https-3A__nam11.safelinks.protection.outlook.com_-3Furl-3Dhttps-253A-252F-252Fjournals.aps.org-252Fprc-252Fabstract-252F10.1103-252FPhysRevC.106.044610-26data-3D05-257C02-257Chaiyan.gao-2540duke.edu-257Cc377941c54a8422e9d1f08de29304dbd-257Ccb72c54e4a314d9eb14a1ea36dfac94c-257C0-257C0-257C638993484610776603-257CUnknown-257CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ-253D-253D-257C0-257C-257C-257C-26sdata-3Dzk9SYGrYrcxJxwt8-252BFliCt7NS2Pig2SW-252F8pnqWT62aw-253D-26reserved-3D0&d=DwIGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=_PD6jg7C_oeff7rIdbHlCiFUHnPsfGvnAy-_snUFmwGcayMCelbsEH5UhHUvMceO&s=CnolF3_ABOz9iYNLF7vO14NmziYEqXzWIP3Y3QGDjdY&e= <https://urldefense.proofpoint.com/v2/url?u=https-3A__journals.aps.org_prc_abstract_10.1103_PhysRevC.106.044610&d=DwMGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=V3XNY-MaMKN2LuAaTdObrA&m=oosjxsZaN9Gcq4x9-K3gOa-hx4fhePCHwCzeuoeHV5x4azGRA7fLcgexBIhP2s9d&s=m6XuJw5eedwpHbjZMJ2eC_Pp-TEjgGtbECM-iGcmaeg&e=>

if you check figure 8, you can see their claim that their new data is
more compatible with PRad than with previous A1 measurments.

Best regards

Adam
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