[Halld-alpha] [EXTERNAL] Slides for meeting tomorrow

[Peter Hurck]

Hi Derek,

Thanks for the comments!

> On 2 Dec 2024, at 14:57, Derek Glazier <Derek.Glazier at glasgow.ac.uk> wrote:
> 
> Hi Peter,
>   Slide 5, Advantage of  lower energies, "double statistics with 3 weeks of running" , Not clear what it is doubling from. Also the plot with result projections does not correspond to the lower energy results, are you planning to update this ?
It is double to what was originally projected. This doubling comes from an older estimation. I think Mark’s initial presentation will clarify if that really is the case as rates might be different. We will see.


>   On the toy slides I would make clear what the generated value of alpha was.
Yes thanks. For everyones benefit: 0.75

>   The statement about the reduced linear polarisation bias is not really made from these toys. The proposal extraction is within 1 sigma of the generated value, while the new value is just over, all be it with much reduced statistical uncertainty. This really needs fits with free linear polarisation. I think the main conclusion of the exercise is the sensitivity to alpha is greatly increased with the lower energy amplitudes.
Maybe. In the proposal we saw that a 1sigma lin pol bias caused a shift from 0.78+-0.08 to 0.71+-0.06 (mean and std of alpha values). In the case of low energies the two numbers are 0.75+-0.02 and 0.73+-0.02. So while both are within one standard deviation of the generated value, the uncertainty is much better and the absolute difference is smaller. I am currently also running a 2sigma and 3sigma bias study to clarify the situation further. As well as a study where linear polarisation is left free in a 2sigma bias case. That all being said, I don’t want to put too much information into this presentation. It might get slightly confusing. We can discuss this all further in our alpha minus meeting.

Cheers,
Peter




> Cheers
> Derek
> 
> 
> .
> From: Halld-alpha <halld-alpha-bounces at jlab.org> on behalf of Peter Pauli <ppauli at jlab.org>
> Sent: 02 December 2024 14:22
> To: halld-alpha at jlab.org <halld-alpha at jlab.org>
> Subject: [Halld-alpha] Slides for meeting tomorrow
>  
> Hi all,
> 
> As we discussed in our last meeting there will be a special Physics WG meeting tomorrow to focus on proposals for low energy running.
> 
> I produced a few preliminary studies to show how helpful it can be to our measurement. The short answer: it looks like it could be extremely helpful.
> 
> Attached are the slides I intend to show tomorrow. There will be some changes as I am still running more fits in different configurations but the main takeaway will not change much.
> I will also add a little bit more text to the result slides to make them easier to understand for people who cannot attend but will look at slides later on. That being said I wanted to send these out to you before I show them and there is not much time left until the meeting. So here is the current state...
> 
> Let me know if you want me to make any changes.
> 
> Cheers,
> Peter
> 
> 
> 
> 
> 
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