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[videbaek <videbaek AT bnl.gov>]

Hi

You should get that with the fill proposed by Carl.



On 2022-01-14 17:55, Ye, Zhenyu wrote:
> Besides low lumi zero field, should we take low lumi full field data
> for alignment?
> This is a question and I don’t know the answer.
>
> Zhenyu
>
> > On Jan 14, 2022, at 4:41 PM, videbaek <videbaek AT bnl.gov> wrote:
> >
> > Hi Elke,
> >
> > we discussed two itesm
> > 1) low luminosity about 10M events. Running it with the 50M NSD seems 
> > perfect and the goal should easily be met.
> > 2) We do have sufficient low-lumi runs already for space charge 
> > calibration, so no additioanlrequests, but #1 wil help.
> > 3)The zero filed tracking alignment do not help the TPC but is of 
> > course important.
> >
> > Gen,Yuri and Flemming
> >
> >
> > On 2022-01-14 12:56, Carl Gagliardi wrote:
> > > Hi Flemming and Gene--  I don’t know what low lumi statistics are
> > > required by the TPC group.  But if 50M+ NSD collisions with field on
> > > will suffice, then the forward cross sections data could likely serve
> > > double duty.
> > > A thought…
> > > Carl
> > > p.s.  Note:  The statistics estimate above is based on the assumption
> > > that a high fraction of the EPDE&&TOFmult0 events will be NSD
> > > collisions, with a z_vtx distribution that follows the collision
> > > diamond.
> > >     We haven’t been in a position to test that assumption yet.  But
> > > the converse has been tested for a mix of semi-hard to hard
> > > scattering.  In particular, Bassam finds that EPDE&&TOFmult0 has
> > > low-to-mid 90s% efficiency for all of the existing FCS triggers, with
> > > only 1~2% variation trigger to trigger.  Also, when running at low
> > > lumi, Bassam has found that 98% of the FCS-triggered events that
> > > include TPC read-out contain a good vertex.
> > > From: Carl Gagliardi <c-gagliardi AT tamu.edu>
> > > Sent: Friday, January 14, 2022 10:28 AM
> > > To: 'Aschenauer Elke-Caroline' <elke AT bnl.gov>; 'STAR sTGC upgrade'
> > > <star-stgc-l AT lists.bnl.gov>; 'Star-fst L' <star-fst-l AT lists.bnl.gov>;
> > > 'Carl Gagliardi' <c-gagliardi AT tamu.edu>; 'Flemming Videbaek'
> > > <videbaek AT bnl.gov>; 'Van Buren, Gene' <gene AT bnl.gov>
> > > Subject: RE: low luminosity running
> > > Hi Elke—
> > > The forward MB cross sections measurement will need 16 hours of beam
> > > with magnet on and __very low__ luminosity.  Specifically, the
> > > non-singly diffractive collision rate per bunch should be no more 
> > > than
> > > a few percent.  2%/bunch would be great; we should be able to live
> > > with 4%/bunch if C-AD can’t get down further.  Under these
> > > conditions, there is no value in having more than 6 bunches in the
> > > fill.  Motivation:
> > > 6 bunch fills at 2%/bunch corresponds to about 9400 NSD collisions 
> > > per
> > > second.  The TPC, which will provide vertexing and measure the
> > > in-bunch pile-up, will only be able to record 2 kHz or thereabouts.
> > > (At these very low rates, that might be pushed to 2500 Hz (TBD), but
> > > not more.)  6 bunches will easily saturate that; more will only
> > > increase the background activity in the TPC with no benefit for the
> > > measurement.
> > > Note:  9400 NSD collisions per second correspond to a ZDC coincidence
> > > rate of 800-900 Hz.
> > > Side note:  These total and recorded collision rates aren’t
> > > “new”.  They are in fact very similar to the values we adopted to
> > > optimize the isobar studies in 2018.
> > > The beam lifetime might be quite long under these conditions.  If the
> > > entire data set can be recorded in one very long fill, that will be
> > > fine.  Otherwise, two fills should be more than adequate.
> > > To achieve the highest practical final precision, we should request
> > > that a Vernier scan be performed in conjunction with the measurement.
> > > Finally, a personal concern:  Beginning next week, I will be out of
> > > pocket teaching class on Tuesdays and Thursdays from 10:15-12:15 BNL
> > > time.  I don’t need to watch the entire running period from Texas,
> > > and likely won’t.  But I definitely think it would be useful for me
> > > to be online for at least the first hour or two of each fill.  I hope
> > > that can be factored into the scheduling.
> > > Hope this is clear!
> > > Carl
> > > p.s.  If C-AD believes it could reliably deliver the beams with a
> > > collision rate of 1%/bunch crossing (even better!), then a 12-bunch
> > > fill would be desired.
> > > p.p.s.  I only expect us to have two “physics triggers” in the
> > > runs, EPDE singles and (EPDE && TOFmult0).  However, there will also
> > > be a number of other highly prescaled trigger-detector only triggers
> > > to facilitate normalization using the TCU scalers.
> > > From: Aschenauer Elke-Caroline <elke AT bnl.gov>
> > > Sent: Thursday, January 13, 2022 10:02 PM
> > > To: STAR sTGC upgrade <star-stgc-l AT lists.bnl.gov>; Star-fst L
> > > <star-fst-l AT lists.bnl.gov>; Carl Gagliardi <c-gagliardi AT tamu.edu>;
> > > Flemming Videbaek <videbaek AT bnl.gov>; Van Buren, Gene <gene AT bnl.gov>
> > > Cc: Aschenauer Elke-Caroline <elke AT bnl.gov>
> > > Subject: low luminosity running
> > > Dear All, as you know the next week we will most likely have lower
> > > luminosity and polarization as there is an issue with the APS. So 
> > > this
> > > might be the perfect time to take our alignment data for the FST and
> > > the sTGC. So the requirement was ZjQcmQRYFpfptBannerStart
> > > This Message Is From an External Sender
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> > > ZjQcmQRYFpfptBannerEnd
> > > Dear All,
> > > as you know the next week we will most likely have lower luminosity
> > > and polarization as there is an issue with the APS.
> > > So this might be the perfect time to take our alignment data for the
> > > FST and the sTGC.
> > > So the requirement was one fill with 28 bunches and low bunch 
> > > current,
> > > with Magnet off. Do we have a luminosity number we want for this.
> > > Is one fill enough.
> > > Are there any measurements we need to do before we are ready for this
> > > alignment run.
> > > Carl you wanted low luminosity running for the cross section
> > > measurement in the forward region, I assume you want it with magnets
> > > on.
> > > Can you please remind me about the exact conditions you want.
> > > Are there any measurements we need to do before we are ready for this
> > > low lumi run.
> > > Flemming and Gene there was also some request for low lumi running 
> > > for
> > > the TPC if I remember correctly, can you remind me what lumi you want
> > > and what conditions.
> > > I would appreciate to have all the info by tomorrow CoB Friday
> > > 01/14/2022
> > > Thanks elke
> > > _Note: Please do not feel obligated to respond to this message 
> > > outside
> > > of your work hours._
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> >
> > --
> > 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
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--
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