[Clas12_verystrange] Fwd: proposal

[Lei Guo]

Marco's comments.



Begin forwarded message:

> From: Marco Battaglieri <battaglieri at ge.infn.it>
> Date: April 30, 2012 11:50:01 AM EDT
> To: "Lei Guo (lguo at jlab.org)" <lguo at jlab.org>
> Cc: "Hicks, Kenneth" <hicks at ohio.edu>, Keith Griffioen  
> <griff at jlab.org>
> Subject: Re: FW: proposal
>
> Dear Lei and other 'very' strange,
> I'm on the same wave-length of Keith's comments: the proposal is  
> valuable but can be (easily) improved.
>
> - Physics motivation: I found it still weak. You should find some  
> deeper reason to justify the Omega measurement other than say that  
> it was not well measured before (I'm clearly exaggerating!). The  
> argument of creating the 3s from scratch is intriguing and probably  
> you may expand to link it to some basic properties of the valence vs  
> sea quarks in baryons. I'm sure there is a huge literature backing  
> to the '60 and '70 that you can cite to  make a stronger physics case.
> The same for the cascade physics. What are we learning with them?  
> Again the mass splitting of doublets is a quantitative argument
> but it is not worked out in details when you report the expected  
> results: is the resolution of CLAS12 good enough to conclude  
> anything on that?  you run simulations and therefore you should be  
> able to report about the expected  mu-md difference. If the CLAS12  
> resolution is not good enough, skip this detailed discussion in pg  
> 11 and replace with some other argument.
> What about the link with the missing baryon physics studied for more  
> than 10 years with the CLAS detector? Is the cascade physics able to  
> provide information about this long-debated topic? I think so.
> I found also very interesting the possibility to measure the elastic  
> scattering omegaN and csiN: It is only reported in Par.D pg 20 but  
> again nothing in the final part about expected results.
>
> - Cross section calculation: I liked the summary in page 26 because  
> we all know that predictions can vary by order of magnitude and  
> checking that different models give more or less the same xsecs is  
> reassuring. I would do something similar to the cascade part. Here  
> you also have real experimental data on your side and it should be  
> easy to give a brief paragraph summarizing the expected cross  
> sections.
>
> - effect of the photon energy: it is not evident how the proposal  
> wold benefit from the increased energy of JLab12: is the energy  
> dependence a valuable information for omega and cascade physics or  
> you just need to be over the production threshold? are you summing  
> all the energy together or binning? this should be clearly stated in  
> the proposal.
>
> - The measurement: you should describe making very clear what you  
> can do with the untagged beam and what with the tagged photons. Pg  
> 36 Sec D. is confusing in my opinion, mixing luminosity of tagged  
> and untagged photon beam. I would rather highlight the physics  
> results you want to achieve and then say that here you can use  
> untagged photons and there you need tagged photons ...
> -- show  the expecetd results on a plot with  simulated points and  
> error bars to  let the reader judge the quality of the new  
> measurement.
> -- background: I completely agree with Keith comment. You need to  
> make clear that the measurement is almost bg free. If possible  
> increase MC statistic of bg in fig 23-24-25:  the huge fluctuation  
> obtained scaling the low statistic sample makes the  picture unclear  
> capturing the attention not on the primary message (signal/bg ratio)  
> but why the bg has such big un-statistical fluctuation!
> -- detrmination of spin/parity: here you really need to support the  
> method by  showing results projected on CLAS12 acceptance. You  
> mentioned the DMA technique but it is not clear to me how well it  
> works with CLAS12 kinematic coverage and the expected statistics.  
> Need to be completed.
> If there is not time to obtain presentable MC results I would skip  
> this part.
>
> - While I found the FT part  concise and well written (just check  
> the consistency of FT-Trck everywhere and use the same notation, not  
> FT-CAL but FT-Cal, FT-Hodo and FT-Trck), giving a e flavor of the  
> detector and its role in CLAS12, there is nothing referring to  
> CLAS12 for hadron detection. You may want to add some kinematic plot  
> showing the 7 particle phase-space and how it is covered by CLAS12.  
> For a non-expert reader, beside the acceptance (fig 22), I would  
> sketch the kinematic of one reaction (eg the omega production)  
> showing K momenta and angular distribution. You say nothing about  
> kaon identification: is the k momentum low enough to safely use the  
> standard CLAS12 Pid in an effective way? or do you need (the) new  
> rich detector? since you rely on massive kaon detection I would  
> spend few words on it.
>
> I would leave to a check-speller the misspelled words and Keith's  
> detailed comments for rewording and phrase changing.
>
> Again, the proposal is well written and I'm sure you just need some  
> extra work to do a greta job.
>
> Cheers
> Marco

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