[Halld-physics] Solenoid - field and physics

[David Lawrence]

Hi Eugene,

    I can help out with a.) to c.) but someone more familiar with PWA 
would need to work on d.).

    In response to Curtis' statement about parameterized M.C., we do 
have HDParSim which I believe is pretty reliable for this type of study. 
I just committed changes today that allow us to run it while scaling the 
nominal errors by some factor. It would be pretty easy to run a lot of 
events through for a complicated final state with 1.1 or 1.2 times the 
nominal charged track resolutions.

Regards,
-David

Eugene Chudakov wrote:
> Hi,
>
> today we ran through a review of the solenoid project, see:
>
> http://www.jlab.org/Hall-D/reviews/Solenoid_Magnet_Internal_Review_Nov09/
>
> They gave a recommendation to show the physics impact of
> running at 80-90% of the planned field (2.2T at 1500A).
>
> The point is that the magnet may not reach 1500A. Before,
> it ran at not more than 1250A. Also, it turns out that the full 
> axial force on coil 2 changes sign at 1350A, which might become a problem.
> This magnet is not expected to quench, but still, if a piece of 
> conductor  moves it may generate a voltage which would look
> like quenching to the control system, which would power 
> the magnet down. Other problems may occur.
>
> Before the review we discussed this question with Curtis. It seems
> that no hard numbers have been collected in one place to be used
> in such occasions.
>
> We must provide this info before the next Lehman review
> (February?). We should assume the detector design finished
> and not adapted to a lower field. 
> Here I list several possible impacts to consider:
>
> a) Higher EM background close to the beam. Result - running
>     at lower luminosity, losses of small angles.
>
> b) Missing mass resolution. Let us take 3-4 reactions and estimate
>     the contamination from reactions with an additional pion (unseen).
>
> c) Particle identification (pi/K/p) from TOF and kinematic fitting.
>     BG for events with charged kaons and no missing particles.
>
> d) The ultimate parameter is the sensitivity to an exotic wave
>     at a certain confidence level, at least for one "gold" reaction.
>
> While a)-c) are simple, c) is complex, but quite important, 
> since similar questions will be asked in future.
>
> Any numbers or suggestions? Who would work on this?
>
> Eugene
> ------------------------------------------------------
> Eugene Chudakov
> http://www.jlab.org/~gen
> phone (757) 269 6959  fax (757) 269 6331
> Thomas Jefferson National Accelerator Facility
> 12000 Jefferson Ave,
> Newport News, VA 23606 USA
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>   

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