Cluster flags

TPC forum post 425:

I am sending a short description of the
TPX cluster finder flags. This is more an Offline issue
but I guess this is a better group since it is a bit
technical.

1) The flags are obtained in the same way other
variables such as timebin and pad are obtained.
I understand that this is not exported to StHit *shrug*.

See i.e. StRoot/RTS/src/RTS_EXAMPLE/rts_example.C

2) They are defined in:

StRoot/RTS/src/DAQ_TPX/tpxFCF.h

The ones pertaining to Offline are:

FCF_ONEPAD           This cluster only had 1 pad.
Generally, this cluster should be ignored unless
you are interested in the prompt hits where this
might be valid. The pad resolution is poor, naturally.

FCF_MERGED           This is a dedconvoluted cluster.
The position and charge have far larger errors
than normal clusters.

FCF_BIG_CHARGE    The charge was larger than 0x7FFF so
the charge precision is lost. The value is OK but the precision is
1024 ADC counts. Good for tracking, not good for dE/dx.

FCF_BROKEN_EDGE       This is the famous row8 cluster.
Flag will disappear from valid clusters
once I have the afterburner running.

FCF_DEAD_EDGE          Garbage and should be IGNORED!
This cluster touches either a bad pad or an end
of row or is somehow suspect. I need this flag for internal debugging
but the users should IGNORE those clusters!

        -- Tonko

TPC forum post 426:

I commited the "padrow 8" afterburner to the DAQ_TPX
CVS directory. If all runs well, you should see no more
peaks on padrow 8. The afteburner runs during the
DAQ_READER unpacking.

However, please pay attention to the cluster finder flags
which I mentioned in an email ago. Specifically:

"FCF_DEAD_EDGE          Garbage and should be IGNORED!
This cluster touches either a bad pad or an end
of row or is somehow suspect. I need this flag for internal debugging
but the users should IGNORE those clusters!"

         -- Tonko

Excess current seen in 2006

The attached powerpoint file from Blair has plots of the excess current seen in the IFC East for 2006.

Modeled distortions

Modeling the Distortion

This can be seen in the following plot, where I again show the distortion to laser tracks at a radius of 60cm (approximately the first TPC padrow) versus Z in the east TPC using distored run 7076029 minus undistorted run 7061100 as red data points. Overlayed are curves for the same measure from models of a half-resistor short (actually, 1.14 MOhm short as determined by the excess current of ~240+/-10nA [a full 2MOhm short equates to 420nA difference]) located at rings 9.5, 10.5, ..., 169.5, 179.5 (there are only 182 rings).

[note: earlier plots I have shown included laser data at Z = -55cm, but I've found that the laser tracks there weren't of sufficient quality to use; I've also tried to mask off places where lasers cross over each other]

The above plot points towards a short which is located somewhere among rings 165-180 (Z < -190cm). As the previous years' shorted rings were rings 169 and 170 ( = short at ring 169.5), it seems highly likely that the present short is in the same place. More detail can be seen by looking at the actual laser hits. The first listed attached file shows the laser hits as a function of radius for lasers at several locations in Z. The dark blue line is a simple second order polynomial fit I used to obtain the magnitude of the distortion at radius 60cm, which I used in the above plot. The magenta line is the model of the half-resistor short at ring 169.5, and the light blue line is the same for ring 179.5 (the bottom two curves on the above plot). Either curve seems to match the radial dependence fairly well.

Further refinement can be achieved by modeling the exact resistor chain. We have a permanent short at ring 169.5 (rings 169 and 170 have been tied together), and have replaced the two 2MOhm resistors between 168-169 and 170-171 with two 3MOhm resistors (see the attached photo of the repair, with arrows pointing to candidate locations for shorts via drops of silver epoxy). So it is more likely that we have a 1.14MOhm short on one of these two 3 MOhm resistors. The three curves in this next plot are:

• red: 1.14MOhm short on a 3MOhm resistor at 168.5, full short at 169.5, 3MOhm resistor at 170.5
• green: 1.14MOhm short on a 2MOhm resistor at 169.5, normal 2.0MOhm resistors at 168.5 and 170.5
• blue: 3MOhm resistor at 168.5, full short at 169.5, 1.14MOhm short on a3MOhm resistor at 170.5

We can also take a look at the data with the resistor in. Here is the same plot as before with a 1.14MOhm short at the same locations, but with an additional compensating resistor of 1.0MOhm. The fact that all the data points are below zero points again towards a short near the very end of the resistor chain, preferring a location of perhaps 177.5 over shorts near ring 170. These plots do not include the use of the 3MOhm resistors, but that difference is below the resolution presented here.

Zoom in with finer granularity between rings (every other ring short shown):

The second listed attached file shows the laser hits as a function of radius for lasers at several locations in Z for the case of the resistor in, again with magenta and blue curves for the model with shorts at ring 169.5 and 179.5 respectively.

Applying the Correction

170.5	171.5	175.5

Gene Van Buren
gene@bnl.gov

Choosing an external resistance for an IFC short

It is clear that when a field cage short is close to the endcap, it is best to add an external resistance to compensate for the amount of the missing resistance from the short as that would restore the current along the length of the resistor chain and only disrupt the potential at the last (outermost) rings instead of along the full length. A short near the central membrane would benefit less from this as restoring the proper current does restore the potential drop between each ring, but leaves almost all rings at a potential offset from the intended potential, essentially tilting the E field over nearly the whole volume.

But the question then comes as to whether we can decide on the best external resistance for minimizing the distortion, to align with the principle that the best distortion we can choose is the one which requires the least correction, in case we're not quite correcting it accurately. To answer that, the distortion modeling was run with a variety of locations for an IFC west 2 MOhm single-resistor short, and a variety of external resistances. The code to run this modeling has been attached as a tar file to this Drupal page in case there is interest to re-run it (e.g. for an OFC short).

Here are the results:

• Left: Surface plot showing the mean r-φ distortion we would get at the first iTPC pad row (radius = 55 cm) averaged over all active west-side z as a function of where the short is located ("ring of short") and how much external resistance is added.
• Right: Same but drawn as contours. The curve of interest to follow, that leads to <distortion>=0, is the one that starts near (ring,external resistance) = (110,0.0) and ends near (180,2.0), as indicated by the red markers. If the short is at ring 160.5, for example, then this curve indicates an external resistance of ~1.05 MΩ minimizes the distortions averaged over all active west-side z.

However, it may be more important to restrict the z range included in the distortion average, as most tracks of interest do not cross the inner pad rows at high z...

• Left: Similar surface plot, but restricting the average to 0 < z < 100 cm.
• Right: The curve of interest to follow in this contour plot, that leads to <distortion>=0, is the one that starts near (100,0.0) and ends near (180,2.0), as indicated by the red markers. If the short is at ring 160.5, then this curve indicates that an external resistance of ~1.25 MΩ minimizes the distortions averaged over 0 < z <100 cm.

Some additional observations:

• The curve of interest should always end close to (180.5,2.0), as that approaches the condition where the external resistance is no different than an internal resistance at the very end of the chain.
• The above is a simplification of what area should be integrated, as tracks with η ≠ 0 cross a variety of z at various radii, complicating the impact on their reconstruction. A track-by-track analysis of impact would be more meaningful, but a lot more work! The modeling shown here can serve as a rough guide to the best external resistance to use, but should not be taken as definitive for all physics.
• It is interesting to note that the model implies that a negative external resistance would help minimize the <distortion> when the short is closer to the central membrane (ring 0). A way to think of this is like having a short at both ends, such that the potentials are too high near the central membrane, and then too low near the endcap, so that the E field tilts one way in the region near the central membrane, isn't tilted at half the drift length, and then tilts the other way near the endcap, resulting in opposing distortions for electrons which drift the full length that serve to cancel each other. This could in principle be achieved by reducing the overall resistance of the Resistor box at the end of the Field Cage chain. The STAR TPC has (as of this documentation) had no persistent shorts near the central membrane that would warrant this approach.

-Gene

Other FC short distortion measurements

I considered the possibility that other measurements might help isolate the location of the short in the TPC. So, using the Modeled distortions, I modeled the effects of adding even more compensating resistance to the end of the IFC east resistor chain. Below are the results for shorts located at ring 165.5 (between rings 165 and 166), 167.5, 169.5, ..., 179.5 as indicated for the colored curves. All plots use a 1.0cm range on the vertical scale so that they can be easily compared. I had hoped that one resistance choice or another would cause more separation between the curves, giving better resolving power between different short locations. But this dependence is small, and actually seems to decrease a little with increased compensating resistance. Remember also that the last laser is at Z of about -173cm.

Also perhaps worth noting is that the 1.0MOhm compensating resistor probably helps reduce the distortions even more than an exact 1.14MOhm would. The latter causes the distortions not to change between the short location and the central membrane, but the former actually causes the distortion to re-correct the damage done between the short location and the endcap!

Compensating resistance [MOhms]	Distortion on first padrow vs. Z
0.0
1.0
1.14
2.0
4.0
20.0

---

Gene Van Buren
gene@bnl.gov

Observed laser distortions

First look

Second look: dedicated runs

No compensating resistor (run 7076029):

With 1 MOhm compensating resistor (run 7076032), which brings IFC east current to correct value within ~20 nAmps, according to 10:27am 2006-03-17 entry in Electronic ShiftLog:

Again, I looked at the distortion as seen be comparing TPC hits from the distorted runs to those from an undistorted run as I did at the beginning of this page (but this time taking distorted minus undistorted). For the undistored, I again have only run 7061100 to work with as a reference. The plots for each Z are in the second listed attached file below, where the top 6 plots are for the no-compensating-resistor run (7076029), and the bottom 6 are the same ones with the resistor in. I also put on the plots the value of the difference from a simple fit (meant only to extract an approximate magnitude) at a radius of 60cm (approximately the first TPC pad row). Those values are also presented in the following plot as a function of Z, confirming the improvement of the distortion with the resistor in place.

These plots seem to point at a short which is occurring somewhere between the lasers at Z = -145 and -115cm.

Gene Van Buren
gene@bnl.gov

Resistor box at the end of the Field Cage chain

 After ring 181, the potentials are determined by a box of resistors which sit outside the TPC. This is well documented, but at the time of this writing is not complete. This was particularly relevant during Run 9 when an electrical short developed inside the TPC between rings 181 and 182 of the outer field cage on the west end (OFCW). Shown here is a plot of the resistors:

Note that the ammeter is essentially a short to ground, while the voltmeters are documented in the Keithley 2001 Manual to express over 10 GOhm of resistance (essentially infinite resistance). The latter only occurs when the input voltage is below 20 V. The voltages at rings 181 and 182 are above 20 V and below 200 V (though actually at negative voltage), so their voltage is scaled by the shown 1.11 and 10.0 MOhm resistors to be stepped down by a factor of x10. The readings are then multiplied by x10 before being recorded in the Slow Controls database.

After Run 9, this box was disconnected and resistances were measured for the OFCW portion. Because the resistors were not separated from each other, equivalent resistances were actually measured. In the below math, R182eq refers to the resistance measured across resistor R_182, while Rfull is the resistance measured between the input to the box from ring 181 to the output for the ammeter. R111 is the combined 10 + 1.11 MOhm pair.

double R111 = 10.0 + 1./(1./1.11 + 1./10000.)
11.11
double R182eq = 0.533 // measured
double Rfull = 2.31   // measured

double pa = R111 - Rfull
double pb = R111*(R111 - 2*Rfull)
double pc = (R182eq - Rfull)*R111*R111

double R181 = (-pb + sqrt(pb*pb - 4*pa*pc))/(2*pa)
2.3614
double R182 = 1./(1./R182eq - 1./R111 - 1./(R181+R111))
0.5841

double R182b = 1./(1./R182 + 1./R111)

double Vcm = 27960.
double Rtot = 364.44   // full chain
double Inorm = Vcm/Rtot
76.720
double V181_norm = Rfull * Inorm
177.22
double V182_norm = V181_norm * R182b/(R181 + R182b)
33.724

double Rshorted = 1./(1./R111 + 1./R182 + 1./R111)
0.5286
double Rmiss = Rfull - Rshorted
1.7814
double Ishorted = Vcm/(Rtot - Rmiss)
77.097
double V181_short = Rshorted * Ishorted
40.750
double Iexcess = Ishorted - Inorm
0.377

Note that many of these numbers would be different for the inner field cages.

External resistors to make up for missing resistance can also be added to the chain here.

Floating Grid Wire Studies

See PPT attachment for simulations of floating grid wires from Nikolai Smirnov which show that the data is consistent with two floating -190V wires in sector 8, and two floating -40V wires in sector 3 (all wires are at -115V when the grid is "open").

GridLeak Distortion Maps

 Using the code in StMagUtilities, these are maps of the GridLeak distortion.

First, this is a basic plot of the distortion on a series of hits going straight up the middle of a sector (black: original hits; red: distorted hits). The vertical axis is distance from the center of the TPC (local Y) [cm], and the horizontal axis is distance from the line along the center of the sector (local X). Units are not shown on the horizontal axis because the magnitude of the distortion is dependence on the GridLeak ion charge density, which is variable.

The scale of the above plot is deceptive in not showing that there is some distortion in the radial direction as well as the r-phi direction. The next pair of plots show a map of the distortion [arb. units] in the direction orthogonal to padrows (left) and along the padrows (right) versus local Y and angle from the line going up the center of the sector (local φ) [degrees].

One can see that the distortion is on the order of x2 larger along the padrows than orthogonal to the padrows. Also, it is clear that there is a small variance in magnitude of the distortion across the face of the sectors.

The next plot shows the magnitude of the distortion [arb. units] along the padrow at the middle of the sectors vs. local Y [cm] and global Z [cm]. The distortion is largest near the central membrane (Z=0) and goes to zero at the endcaps (|Z| ≅ 205 cm), with a linear Z dependence in between, which flattens off at the central membrane and endcap due to boundary conditions that the perturbative potentials are due to charge in the volume and are constrained to zero at these surfaces.

GridLeak Simulations

Data for STAR TPC supersector.   05.05.2005  07.11.2005
Jon Wirth, who build all sectors provide these data.

Gated Grid Wires: 0.075mm Be Cu, Au plated, spacing 1mm
Outer Sector 689 wires, Inner Sector 681 wires. Total 1370 wires per sector

Cathode Grid Wires: 0.075mm Be Cu, Au plated, spacing 1mm
Outer Sector 689 wires, Inner Sector 681 wires. Total 1370 wires per sector

Anode Grid Wires:0.020mm W, Au plated, spacing 4mm
Outer Sector 170 wires, Inner Sector 168 wires. Total 338 wires per sector
Last Anode Wires: 0.125mm Be Cu, Au plated
Outer Sector 2 wires, Inner Sector 2 wires. Total 4 wires per sector

We are most interested in the gap between Inner and Outer sector, where ion leak is important for space charge. On fig. 1 wires set is shown. The distance between inner and outer gating grid is 16.00 mm. When Grid Gate is closed, the border wires in Inner and Outer sectors have -40V, each next wire have -190V and after this pattern preserved in whole sector - see fig. 2. When gating grid is open, each wire in gating grid have the same potential -115V. Above grid plane we have a drift volume with E~134V/cm to move electrons from tracks to sectors and repulse ions to central membrane. Cathode plane has zero voltage, while anode wires for outer sector holds +1390V and for inner sector +1170V.

Fig. 1. Wire structure between Inner and Outer sector.

Fig.2 Voltages applied to Gating Grid with grid closed.

Another configurations of voltages on gating grid wires are presented on fig.3. All these voltages are possible by changing wire connections in gating grid driver. Garfield simulations should be performed for all to find a minimum ion leak.

Fig.3 Different voltages on closed gating grid (top: inverted, bottom: mixed).

This is a key for Nikolai's files: there are 4 sets of files in each set there is simulation for Gating Grid voltages on last wires. Additionally he artificially put a ground shield on the level of cathode plane and simulated collection for last-thick anode wire and also ground shield and last thin anode wire.

Setups:	Standard	Inverted	Mixed	Ground Strip	Ground Strip and Wire
Equipotentials	PS	PS	PS	PS	PS
Electron paths	PS	PS	PS	PS	PS
Ion paths (inner sector)	PS	PS	PS	PS	PS
Ion paths (outer sector)	PS	PS	PS	PS	PS

GridLeak: Gain Study

First note: the ever-present problem that our model goes to zero distortion at the endcaps, while the measured distortions do not appear to do so (though the distortion curves should flatten out [as seen in the above plots] as a function of Z near the endcap and central membrane due to boundary conditions on the fields in the TPC).

Second note: I have not excluded sector 20 from these plots, which is partly to explain why the east half (z<0) has slightly less distortions than the west in these profile plots. In reality, east and west were about even for a normal run (distortions excluding sector 20).

Here is the z-phi plot for Low (it's almost difficult to see the distortion reduction in the z-phi (in "o'clock") plot for Half):

Third note: (though not too important for this study because we generally ignore east/west comparisons) the sectors between 1-6 o'clock already tend to show somewhat less distortion than the sectors at 7-12 o'clock, and because it is true on both halves of the TPC, it is more likely to be due SpaceCharge azimuthal anisotropy than asymmetries in the endplanes. Here are the distortions at |z|<50 for east (red) and west (blue) as a function of phi in "o'clock" where one can see the already present asymmetry, explaining why sectors 1-6 are already less distorted in the Norm run than sectors 7-12:

We have to normalize to sectors 7-12 to see the drop in distortions as it the runs are taken at different times when the luminosity of the machine, and therefore the distortion normalizations, are different. Here are the ratios from sectors 1-6 / sectors 7-12:

And the double ratios to see the drop in the Half and Low runs w.r.t. the Norm run:

These plots show ratios in the Z = 25-150cm range of about 0.86 and 0.59 respectively, or reductions of about 14% and 41% give or take a few percentage points. Data beyond 150cm tends to be poor and there's little reason to believe that the ratio really changes by much there. However, there does appear to be some shape to the data, which is not understood at this time.

Another way to calculate the difference in distortions is to take a linear fit to the slope of the distortions between z = 25-150cm. Those fit slopes are:

Low:
1-6: 0.000250 +/- 0.000019
7-12: 0.000420 +/- 0.000024
Half:
1-6: 0.000365 +/- 0.000023
7-12: 0.000433 +/- 0.000025
Norm:
1-6: 0.000401 +/- 0.000024
7-12: 0.000422 +/- 0.000023

[Half(1-6)/Half(7-12)] / [(Norm(1-6)/Norm(7-12)] = 0.89+/-0.11 (12%)
[Low(1-6)/Low(7-12)] / [(Norm(1-6)/Norm(7-12)] = 0.63+/-0.08 (12%)
Inner reduction = (11 +/- 11)%
Outer reduction = (26 +/- 11)%
Total reduction = (37 +/- 8)%

Gene Van Buren

SpaceCharge studies

 Studies of SpaceCharge in the TPC.

TPC Sector Alignment Using Particle Tracks for Run 8

TPC Sector Alignment Using Particle Tracks for Run 8

TPC group meetings 2020-

   The  production for Run22 pp500 does not have *event.root files, and thus it  cannot be used for dE/dx calibration.

See, for example, 

/star/data113/reco/production_pp500_2022/ReversedFullField/P24ib_calib/2021/355/22355023/

TPC meeting January 23, 2025

Present Emmy Yuri, Gene Flemming, Aihong

Excused: Richard, Jim

Software:

Space charge todo – Gene

Yuri- GMT code not in repository has to be moved to repository by Gregory.

Waiting for this to complete so he can add the GMT infor to putput files (mudst and picodst)

Emmy presented a short update on centrality dependence of mass difference

See slide 3 and 4. Statistics insufficient outside +-30 cm

Gene: maybe some influence by vertexfinder (minuit) relative to beam line

AOB 

Production run 19 going, Ask Yuri to check de/dx . Does not see issues.

Yuri will be gone for next two weeks.

Emmy’s updated file on https://drupal.star.bnl.gov/STAR/subsys/tpc/tpc-group-meetings

— η dependence deuteron peak position can be explained by energy loss in beam pipe, IFC, and TPC gas.

 

 

— were almost at 15% until Tonko fixed many yesterday
 status since day 200 

TPC meeting June 27, 2024

Present: Alexei, Jim, Frank, Dan, Yuri, Mattheu,  Gene and Flemming

-hardware:

Position and composition of NMR probe has been documented by Alexei. An entry to drupal blog has been added https://drupal.star.bnl.gov/STAR/blog/videbaks/NMR-probes.

This would require an update to detector description in GEANT as it is in the active are of BBC and EPD.

Tim has order additional interface so the NMR readout can be attached to slow control.

Shift crews as usually struggles to operate laser well. Alexei provides on hand training to crew, and this helps a lot.

-software

Yuri presented at the Tuesday mgt meeting status, and a  detailed plan for alignment and calibration needed for the FXT target data and beyond, The plan was well received by mgt and will form basis for work in the coming month , including calibrations tasks for BTOF, eTOF,… The presentation is available at https://drupal.star.bnl.gov/STAR/event/2024/06/25/STAR-management-meeting/TPC-Alignment2024

-electronics

Usual loss of ~1 RDO per day of running. Several have been brought back to life by Tonko when there is sufficient downtime available to diagnose issues (prom’s power distribution).

Fairly stable overall.

-              QA team identified data where offline cluster finding failed to read adc files causing  memory overwrites and leaks. Issue was identified by Tonko, and relates only to offline cluster finding. Pull request has been generated.

-software

Yuri is working on optimizing t0 for FXT to minimize residual track breaking, using position of target (200 – 200.5 cm).

Richard T. and Jae N. is working with Gene on 2022 space charge. Fill-by-fill correction is proceeding well.

TPC meeting June 13, 2024

Present: Yuri, Alexei, Gene, Jim, Flemmig, Tommy, Dan

Hardware:

Worked on magnetometer interface. The RS232 does not seem to work, had help from David, Tim. We agree to have shift crew record setting once per hour. Now instituted. Stability seems to be in order .1 %% much better than current reading. Alexei will pursue options for readout to slow control.

Laser:

Laser in general are not great. Weak laser (eats or west?) crew not tuning well while taking data.

Electronics:

Kind of steady: loosing maybe 1 RDO per day; being brought back from tonko when time available (ie no beam)

Software:

Pp500 run 22 data proceeding. Now on pass 2. Mostly looks good and improved, but a few fills semms not to have converged in pass  2. Will reapet, but continue to pass 3 with the starting with pass 2 results.  The beamline calibration also need to be repeated with the pass 2 calib.

Yuri has a new alignment (super sectors) 2024  and applied it to the all of the run 19-21 FXT data that showed a large CM track breaking as found by the Davis group. It seems to have fixed that problem see https://www.star.bnl.gov/~fisyak/star/Tpc/Alignment/FXT_CM_Tracks_splitting/

This is very encouraging. Yuri will continue with look at t0 adjustments, and once that done like to make a TFG production of about 100M events on 11.5 GeV data (020) to check results, in particular K0s mass dependence on phi-eta .

TPC meeting 2/22 2024

Present : Jim,Yuri,Tommy, Gene and Flemming

Hardware

  Last repairs of RDO (2) should be done in next two weeks; closeout approaching

  Alexei reported during week

“I finished measurements of target displacement on TPC wheel versus actual position. For all holes target dropped vertically down due to target gravity.

 I did only inner holes on wheel. There are too  difficult to measure others.”

And provided numbers to Yuri. Resoultion in survey should be around 150 microns.

Software

a)  work on space charge calibration of pp 200 for 2022 has continued . Studied 5 fills with high statistics.

The runs are long and some jobs were killed due to 3 day limit.

Comparisons of fill vs ZDC rate shows

1) nice linearity with ZDC rate which is good

2) significant difference between fills corresponding to 4-5 mm DCA.

So seems necessary to have space charge done per fill.

b) Continued looking at matching between TPC and BEMC towers. Confirmed that indeed the phi-definitions are same between subsystems as should be. So issue of reduced matching is in area behind sector 18. Other plots (e.g. h+/h- issues) does not show any issues with sector 18 vs. time.

Gene suggested looking if it could be a BEMC issue electronics. Matching looked slightly off.

c) discussion on track matching to eTOF, that was also the subject to an earlier meeting today. New information appear during meeting, and issue may very well be a space charge issues. Have suggested eTOF group to review matching in FF and RFF setting for OO system to confirm this is a space charge driven.

And the expected de/dx (Bichsel fuction) is:
 
1. For triton : dedx_expected = charge*charge*(TMath::Exp(Bichsel::Instance()->GetMostProbableZM(TMath::Log10(p*TMath::Abs(charge)/mass), 1)));
2. For helium3 : 
    Float_t ParfHe3Mean[4] = {29.3642,-0.983422,0.0958638,0.169811};
    dedx_expected = ParfHe3Mean[0]*TMath::Power(p, ParfHe3Mean[1] + ParfHe3Mean[2]*log(p) + ParfHe3Mean[3]*log(p)*log(p));

TPC meeting 11/30/23

Present: Yuri, Jim, Gene, Rongrong, Flemming, Irakli, Alexei, Weizhang

Discussion on tp high0 pt resolution. (cosmic, J/psi)

Lead in presentation by Rongrong Link

Presented results from looking at cosmics, 2011,2014 and 2018. 

Irakli will take a look at these data, after having gotten location of these.

Rongrong will update presentation included opening angle vs pt for J/psi to see

If this can possibly explain some of the flat dependence of resolution vs. pt

Will also take a look of h-/h+ at high pt as Gene used this as one measure for QA.

Hardware:

Preparing for survey, cleaning holes, addition pins in order to get better handled of TPC position relative to magnet. Will bring up request for survey at next ops meeting.

Fixing of recent leak underway; gotten spare connectors.

Electronics:

According to Tim they will likely wait until the hardware repairs (leak) and survey is done, to finish the TPC electronics repirs.

Software:

Space charge correction; Quite good after 3 iterations, put in DB and will be used for test production. Will proceed to 4^th but needs more statistics.

Test production fails for some DAQ files (FST issues causes crash)

Yuri back and will go back to looking at de/dx, alignment.

Has still outstanding pull request that has to be approved.

Minute TPC meeting June 22, 2023

Present:

Jim, gene, alexei, tommy, , flemming, yuri

Hardware

--quote for cathode  is been requested for 6okV  60 kV supply , 14k$ and lead time 28 weeks.

This is what Tom Hemmick is using for sPHENIX, and Alexei decided to pick the same after discussion with Tom.

- gas impurity showed again with the most recent exchange of 6-pack and the vDrift is down to 

What happened with the first of new supplier.

Methan left for 12 days. Note after meeting. Prahsanth said today(Friday) that he expects delivery today of 2 six-packs

-Could be possible have a sample bottle, and check composition gas tomography e.g. in Chemistry? (FV). Alexei will follow up

Electronics –

3 more sectors 4-6 now  with daq5k . Some readout issue with adc’s for sector 4-1, clusters ok

Software

- pull requests that has been stalled (some of Yuri’s) have been approved

 finished up calibration fixed target dataset. Looks good. Will need a couple of more days  for checking. Should be done by Monday.

The 19.6 is in database. Gene will start production. 7.7 needs update due to minor update (a few % correction)

Working on combined PID.

Yuri had asked Tommy to look at the production data for RFF and FF production data full field data going back to 2010 and look at the quantity

“dY in SCS versus sector and Z zx projection”. 

Summary plots as well as summary table shows clear modulation for FF data are in in https://www.star.bnl.gov/~ctsang/Alignment/dYS/

Tommy’s table summarizing this is in

https://www.star.bnl.gov/~ctsang/Alignment/dYS/summary.html

The summary from Tommy is

Signification sinusoidal modulation in cluster – tracks vs sector is only found in Full field results on 2021. It is not seen in Reversed full field or old full field results. Therefore a special rotation should be applied to FF data on 2021.

Recall that this was  not supported by Alexei measurements. Suggest to introduced rotation for run 21.

TPC performance

 Documentation on performance of the TPC
 

• Run 15 200 GeV p+Al Hit Errors
• Run 15 200 GeV p+Au Hit Errors
• Run 15 200 GeV p+p Hit Errors
• Run 14 (200 GeV Au+Au) TPC Hit Errors
• Run 14 (15 GeV Au+Au) TPC Hit Errors
• Run 13 TPC Hit Errors (days 74-128) and Run 13 TPC Hit Errors (Days 129 -161) (pp510)
• Run 12 Cu+Au TPC Hit Errors
• TPC hiterrors Run12 U+U 193 GeV
• Run 12 pp510 hit errors
• Run 12 pp200 (before dE/dx calibration)
• TPC Hit Errors (Run11 Au+Au 27 GeV)
• Hit errors for Run11 Au+Au 200 GeV dataset
• TPC Hit Errors (Run11p+p 500 GeV)
• TPC Hit Errors (Run 9), both pp500 and pp200, and re-calibrated TPC hiterrors Run9 p+p 200 GeV RFF
• TPC Hit Errors (2008) (pp200, not certain it was Run 8 or an earlier dataset)

• TPC Pt and DCA resolution

error_xy = sqrt([0]+[1]*((200.-y)/100.)/(cos(x)*cos(x))+[2]*tan(x)*tan(x))
error_z  = sqrt([0]+[1]*((200.-y)/100.)*(1.+tan(x)*tan(x))+[2]*tan(x)*tan(x))

error_xy->SetParameters(0.0004,0.0011513,0.01763);
error_z ->SetParameters(0.00093415,0.0051781,0.014985);

error_xy->SetParameters(0.0012036,0.0011156,0.063435);
error_z ->SetParameters(0.0026171,0.0045678,0.052361);