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[videbaek <videbaek AT bnl.gov>]

Hi Hongwei,

Thanks for implementing this.
I think we could consider strengthening th criteria. This woud allow any 
track that hits th cycinder to be tagged. One suggestion would be to 
require
one of two conditions a) cylinder hit AND hit in second disk (182) or b) 
hit in disk 1 (148) and hit in disk(2). This would match the criteria 
for the two trigger evpw/e and ewpdw.tof , and give higher probability 
for also hits in stgc.
Of course the reduction is still large w/o this extra criteria.

F


On 2021-11-22 23:15, Hongwei Ke wrote:
> Hi Fleming and all
>
> Thank you for the info. Here is what I have implemented and ready for
> test.
>
>         * I use bField = 1e-6 Tesla instead of zero to make sure all
> extrapolation functions work properly. This value is chosen
> arbitrarily. As long as it is not zero, the math should be correct.
>         * To "match FST", I extrapolate TPC tracks to three surfaces.
>
>         * A cylinder: r = 36cm, 148 <= z <= 182cm  # cylinder geometry is
> easier to deal with
>         * A disk r <= 36, z = 148
>         * A disk r <= 36, z = 182
>         * These values can be changed easily. If needed, they can be
> implemented as Run Control parameters that can be turned by shift crew
> run-by-run.
>
>         * The track extrapolation is done in sequence. If there is one track
> hits any of those three surfaces, it is a match and the event will be
> tagged.
>         * From my standalone test on a signal daq file from run 22326045,
> 748 out of 30374 events are tagged. The ratio is ~2.5%.
>
> Best regards,
> Hongwei Ke
>
> > On Nov 22, 2021, at 4:05 PM, videbaek <videbaek AT bnl.gov> wrote:
> >
> > Hi Hongwei,
> > cc Xu
> >
> > With the actual positions  the z range should rather be 148 to 182,
> > As Xu says you can ether use a square for the xy cut or maybe better
> > a circle with radius say 36(40)
> >
> > F.
> >
> > On 2021-11-22 15:59, Xu Sun wrote:
> > Hi Hongwei,
> > The radius of the FST disk is about 31cm, therefore, I quote 40cm
> > for
> > both x and y.
> > Not sure why Carl quotes y = 0, maybe Carl could comment.
> > Best,
> > Xu
> > On Mon, Nov 22, 2021 at 3:57 PM Hongwei Ke <kehw AT rcf.rhic.bnl.gov>
> > wrote:
> > Hi Xu,
> > Carl’s number in his Nov 20 email to star-ops are a little
> > different.
> > Would it be possible for L4 to identify those events with a cosmic
> > track that projects through the rectangle:
> > -40 < x < +40
> > 140 < z < 180
> > At y=0
> > Which one should I use?
> > Best regards,
> > Hongwei Ke
> > On Nov 22, 2021, at 12:28 PM, Xu Sun <sunxuhit AT gmail.com> wrote:
> > Hi Hongwei,
> > As discussed in today's 10 clock meeting, please find the FST
> > position below:
> > x & y: -40 to 40 cm
> > z: 140 to 180 cm.
> > Hope this helps.
> > Best,
> > Xu
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> --
> Flemming Videbaek
> senior scientist
> videbaek @ bnl.gov [1]
> Brookhaven National Lab
> Physics Department
> Bldg 510D
> Upton, NY 11973
>
> phone: 631-344-4106
> cell     :  631-681-1596
>
>
>
> Links:
> ------
> [1] http://bnl.gov

--
Flemming Videbaek
senior scientist
videbaek @ bnl.gov
Brookhaven National Lab
Physics Department
Bldg 510D
Upton, NY 11973

phone: 631-344-4106
cell     :  631-681-1596