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

[gasparan]

  Thanks Patrick for your very detailed explanation on this paper.
  My knowledge based on several lengthy discussions with MAMI people also
  agrees with your statements.
  Hope they will be able to take good data during this September run.

  Ashot


On 2025-11-22 03:13, Patrick Achenbach wrote:
> 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
> 
> Phone: 919-660-2622
> 
> www.tunl.duke.edu/~mep [1]
> 
> ***********************************************
> 
>  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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjournals.aps.org%2Fprc%2Fabstract%2F10.1103%2FPhysRevC.106.044610&data=05%7C02%7Chaiyan.gao%40duke.edu%7Cc377941c54a8422e9d1f08de29304dbd%7Ccb72c54e4a314d9eb14a1ea36dfac94c%7C0%7C0%7C638993484610776603%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=zk9SYGrYrcxJxwt8%2BFliCt7NS2Pig2SW%2F8pnqWT62aw%3D&reserved=0
> [2]
> 
> 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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> PRad at jlab.org
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> [3]
> 
> Links:
> ------
> [1] 
> 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=
> [2] 
> 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=
> [3] https://mailman.jlab.org/mailman/listinfo/prad