53 GeV run

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Some expectations of multi-hit:

(This study has been corrected since its original posting.  Originally, I had assumed that all rings had 24 phi segments, but in reality, ring 1 (TT1) only has 12)

Update 15 June 2017: A first analysis of the ADC spectra bear out the expectations of the analysis below quite well!  See drupal.star.bnl.gov/STAR/blog/lisa/multi-mip-events-2017-epd-auau-54-gev

As seen on the attached spreadsheet at drupal.star.bnl.gov/STAR/system/files/53GeVexpectations_1.xlsx, based on PHOBOS measurements at 62.4 GeV (see inspirehep.net/record/876609), we can expect the EPD to light up!  This beam energy is higher than what the EPD was designed for, but we will be fine.

(That spreadsheet has been updated to include calculations for 200 GeV and for 19.6 GeV.)

The average number of hits expected in each tile is of order unity, and the multi-hit probabilities can be estimated using Poisson statistics.  The spreadsheet attached uses a scan of the PHOBOS data for 62.4 GeV collisions (figure 16) at about 6% centrality.  The average and multi-hit probabilities depend on the collision vertex position.  Some examples are shown in the screenshots below.

Here, we see that for collisions not far from the center of the TPC (|Vz|<75 cm), we will be just fine: 6-MIP hits are at the sub-percent level:
Here is for collisions at the center of the TPC:


Here is for collisions at Vz=-75 cm:


But if we come a lot closer to the detector (say Vz=-2.75 cm, which is outside the TPC!!), then we get blasted:

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Mapping used in the Au+Au 53 GeV run
(Right-click and do "view image" to see it blown up, if you need details on QT address and channel number)

Bias Scan

Bias Scan runs taken by Rosi.

No	Run No	Voltages: Vset / Vbias (*)	Prashanth's initial results	Mike's Results
1	18089047	56.5 / 58.3	Bias Scan	drupal.star.bnl.gov/STAR/system/files/BiasScan.pdf See below for analysis
2	18089055	55.5 / 57.3
3	18089063	57.5 / 59.3
4	18089065	54.5 / 56.3
5	18090003	58.5 / 60.3

Root files for above runs are here: rcasxx:/gpfs01/star/subsysg/EPD/sprastar/EPDHists

(*) Bias voltage (Vbias) is 1.8 V above the Vset value one sets with the TUFF box.  The relevant clip of Gerard's mail:
"The actual bias on the SiPM is higher than the setpoint by about 0.9 V for the
VCOMP (temperature compensation) plus about 0.9 V for the preamp input voltage
(the regulator regulates the anode voltage to -(VSET+VCOMP)*(1 +/-1% error) )"

Note that Hamamatsu specs Vbias at about 57.7 V, for this initial batch of SiPMs:
drupal.star.bnl.gov/STAR/system/files/S13360-1325PE%20specs%20initial%20150.pdf

Mike's analysis of the bias scan - 9 April 2017

• We don't want to wander too far away from Hamamatsu's recommendation of Vbias=57.7 V (Vset=55.9 V), since the signal increases linearly with bias voltage (see plots), and the dark current increases exponentially with bias voltage.
• Looking carefully at the 6 FEE groupings (one FEE handles odd or even tiles from a supersector):
  • 4 groupings (PP4 even, PP5 odd, PP6 odd, PP6 even) give MPV ~ 45 ADC counts for Vset ~ 56.5 V
  • PP4 odd gives MPV ~ 60 ADC counts for Vset ~56.5 V: this is because it is read through QT32c which has higher gain
  • PP5 even gives MPV ~ 24 ADC counts for Vset ~ 56.5 V: This may be due to one of the following reasons:
    1. This fee has a lower gain than the others
    2. This QT board has lower gain than the others.
       • This may be checked by swapping inputs with another QT board
    3. The fiber-to-SiPM connection (FSC) is worse than the others.
       • In principle, this could lead to a highter WID/MPV ratio due to reduced photon number and higher Poisson fluctuations, which is not observed.
       • Nevertheless, I kind of suspect #3
• The "gain" is rather linear with Vset, so we can "peak-match" the various channels by adjusting Vset such that the MIP peak is always at the same location.  However, this should only be done within limits.  It makes no sense to lower Vbias a lot, just to "compensate" for the high gain of the QT32c or to raise it a lot to "compensate" for the low gain of PP5 even.
• Therefore, I suggest to proceed as follows:  Set Vset such that
  • MPV = 45 ADC counts for PP4 even, PP5 odd, PP6 odd, PP6 even
  • MPV = 60 ADC counts for PP4 odd
  • MPV = 25 ADC counts for PP5 even
• The Vset values, using this criteria, may be found at drupal.star.bnl.gov/STAR/system/files/VsetValues.txt
  • I set Vset by hand to 56.5 for 3 of the 93 fits that failed.

BitMap Checking

Eleanor has given following information to start with:

No	Run Number TAC min =50	Run Number TAC min =80	Run Number QTB TAC min =80 QTC TAC min =40	Run Number QTB TAC min =80 QTC TAC min =47	Run Number QTB TAC min =82 QTB ADC TH=80 QTC TAC min =40	EPQ_Algorithm_Latch (for QTB & QTC)	EPD_QT_Output_Latch_Delay (for QTB & QTC)	% Miss match 0x18 Algo v5.2	% Miss match 0x16 Algo v6.d	% Miss match 0x12 Algo v6.4	% Miss match 0x10 Algo v6.4
1	18129066	18130041	18131026	18150036	18158037	1	0
2	18129067	18130042	18131027	18150037	18158038	1	20
3	18129068	18130043	18131028	18150038	18158039	1	40
4	18129069	18130044	18131029	18150039	18158040	1	60
5	18129070	18130045	18131030	18150040	18158041	1	80
6	18129071	18130046	18131031	18150041	18158042	1	100
7	18129072	18130047	18131032	18150042	18158043	1	120
8	18129073	18130048	18131059	18150043	18158044	2	0
9	18129074	18130049	18131060	18150044	18158045	2	20
10	18129075	18130050	18131061	18150045	18158046	2	40
11	18129076	18130051	18131062	18150046	18158047	2	60
12	18129077	18130052	18131063	18150047	18158048	2	80
13	18129078	18130053	18131064	18150048	18158049	2	100
14	18129079	18130054	18131065	18150049	18158050	2	120
15	18129080	18130055	18131066	18150050	18158051	3	0
16	18129081	18130056	18131067	18150051	18158052	3	20
17	18129082	18130057	18131068	18150052	18158053	3	40
18	18129083	18130058	18131069	18150053	18158054	3	60
19	18129084	18130059	18131070	18150054	18158055	3	80
20	18129085	18130060	18131071	18150055	18158056	3	100
21	18129086	18130061	18131072	18150056	18158057	3	120
22	18129061	18130062	18131033	18150057	18158058	4	0
23	18129062	18130063	18131034	18150058	18158059	4	20
24	18129063	18130064	18131035	18150059	18158060	4	40
25	18129064	18130065	18131036	18150060	18158061	4	60
26	18129065	18130066	18131037	18150061	18158062	4	80
27	18129059	18130067	18131038	18150062	18158063	4	100
28	18129060	18130068	18131039	18150063	18158064	4	120
29	18129087	18130069	18131073	18150064	18158072	5	0
30	18129088	18130070	18131074	18150065	18158073	5	20
31	18129089	18130071	18131075	18150066	18158074	5	40
32	18129090	18130072	18131076	18150067	18158075	5	60
33	18129091	18130073	18131077	18150068	18158076	5	80
34	18129092	18130074	18131078	18150069	18158077	5	100
35	18129093	18130075	18131079	18150070	18158078	5	120
36	18129094	18130076	18131040	18150071	18158079	6	0
37	18129095	18130077	18131041	18150072	18158080	6	20
38	18129096	18130078	18131042	18150073	18158081	6	40
39	18129097	18130079	18131043	18150074	18158082	6	60
40	18129098	18130080	18131044	18150075	18158083	6	80
41	18129099	18130081	18131045	18150076	18158084	6	100
42	18129100	18130082	18131046	18150077	18158085	6	120
43		18130083	18131080	18150078	18158086	7	0
44		18130084	18131081	18150079	18158087	7	20
45		18130085	18131082	18150080	18158088	7	40
46		18130086	18131083	18150081	18158089	7	60
47		18130087	18131084	18150082	18158090	7	80
48		18130088	18131085	18150083	18158091	7	100
49		18130089	18131086	18150084	18158092	7	120

Discriminator Threshold Scan

Following is worked  out by Valentino, Stephen <svalentino@bnl.gov>

Following runs are taken
Gate values are set to best values in following runs.

	Run Number	QTB  Discriminator Threshold	QTC_Discriminator_Threshold
1	18116044	16 (0x00F) =  8 mV	64(0x03F) = 11 mV
2	18116047	32 (0x01F) = 14 mV	128(0x07F) = 28 mV
3	18118021	24 (0x017) = 11 mV (linear interpolation)	96(0x05F) = 19.5 mV (linear interpolation)
	Phase II
4

Here is first analysis:
drupal.star.bnl.gov/STAR/system/files/EPD_ThresholdScan_Prashanth_05012017.pdf

Timing In

Timing scan after installing QT32c board on 03/17/2017

#EPD Trigger is present in all following runs(i.e. +BBC_TAC +BBC_E + BBC_W)
Timing Scan
-----------

Pre-Post	Run#	QTb Start	QTb End	QTc Start	QTc End	TAC Stop
Pre=2, Post=2	18066043	8	24	not precent	not precent	48
Pre=2, Post=0	18076064	0	16	0	16	56
Pre=0, Post=2	18076065	0	16	0	16	56

Root files for above runs are here: rcasxx:/gpfs01/star/subsysg/EPD/sprastar/EPDHists
I have attaced the results for run above runs and run 18066043.
Run 18066043 was taken earlier for QTb STAR Delay =8 and QTb END Delay = 24 ns.

Then we did the Gate scan in 2ns. During this step we recorded only pre, post = 0,0 crossings.
From this gate scan we noticed QTb STAR Delay =0 and QTb END Delay = 16 ns is best.
From the runs 18076064 and 18076065 it seems we are in pre = 1 crossing for QT32 'b' board, i.e PP-4 even, PP-5 odd, PP-6 (even & odd)

and QT32 'c' board in trigger crossing.
Timeing seems completely messed up.
Let me thing more in the morning






Gate Scan
--------
Following runs are taken on March 19th.
In the following runs EPD Trigger is updated so we have now JP2 (i.e. +BBC_TAC +BBC_E + BBC_W + JP2)

No	Run Number	Gate Start QT 32 b	Gate End QT 32 b	Gate Start QT 32 c	Gate End QT 32 c	TAC Stop	Data Start Address	Initial Study by Prashanth	Mike's PrePost study and Comments
1	18078043	0	16	0	16	56	c=8, b=8	EPD_plots_18078043.pdf	PrePost=-1 1st run of the fill
2	18078044	4	20	4	20	56	c=8, b=8	EPD_plots_18078044.pdf	PrePost=-1
3	18078045	8	24	8	24	56	c=8, b=8	EPD_plots_18078045.pdf	PrePost=0
4	18078046	12	28	12	28	56	c=8, b=8	EPD_plots_18078046.pdf	PrePost=0
5	18078047	16	32	16	32	56	c=8, b=8	EPD_plots_18078047.pdf	This run was stopped for beam squeeze
6	18078048	16	32	16	32	56	c=8, b=8	EPD_plots_18078048.pdf	PrePost=0
7	18078049	20	36	20	36	56	c=8, b=8	EPD_plots_18078049.pdf	stopped for polarization measurements
8	18078050	20	36	20	36	56	c=8, b=8	EPD_plots_18078050.pdf	PrePost=0
9	18078051	24	40	24	40	56	c=8, b=8	EPD_plots_18078051.pdf	PrePost=0
10	18078052	28	44	28	44	56	c=8, b=8	EPD_plots_18078052.pdf	PrePost=0  Taken By Yang Wu
11	18078053	32	48	32	48	56	c=8, b=8	EPD_plots_18078053.pdf	PrePost=0
12	18078054	36	52	36	52	56	c=8, b=8	EPD_plots_18078054.pdf	PrePost=0
13	18078056	40	56	40	56	56	c=8, b=8	EPD_plots_18078056.pdf	PrePost probably 0 (bad stats)
14	18078057	44	60	44	60	56	c=8, b=8	EPD_plots_18078057.pdf	PrePost probably 0 (out of gate)
15	18078058	48	64	48	64	56	c=8, b=8	EPD_plots_18078058.pdf	PrePost=0?  or 1?
							c=8, b=8
Negative Scan
16	18082042	0	16	0	16	56	c=8, b=8	EPD_plots_18082042.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
17	18082043	107(0)	123(16)	107(0)	123(16)	56	c=8, b=8	EPD_plots_18082043.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
18	18082044	103(-4)	119(12)	103(-4)	119(12)	56	c=8, b=8	EPD_plots_18082044.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
19	18082045	99(-8)	115(8)	99(-8)	115(8)	56	c=8, b=8	EPD_plots_18082045.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
20	18082046	95(-12)	111(4)	95(-12)	111(4)	56	c=8, b=8	EPD_plots_18082046.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
21	18082047	91(-16)	107(0)	91(-16)	107(0)	56	c=8, b=8	EPD_plots_18082047.pdf	QT32b in PrePost=-1 QT32c in PrePost=0
22	18089004	87(-20)	103(-4)	87(-20)	103(-4)	56	c=8, b=8	EPD_plots_18089004.pdf
23	18089007	83(-24)	99(-8)	83(-24)	99(-8)	56	c=8, b=8	EPD_plots_18089007.pdf
24	18089008	79(-28)	95(-12)	79(-28)	95(-12)	56	c=8, b=8	EPD_plots_18089008.pdf
25	18089009	75(-32)	91(-16)	75(-32)	91(-16)	56	c=8, b=8	EPD_plots_18089009.pdf
26	18089010	99(-8)	115(8)	99(-8)	115(8)	56	c=8, b=7	EPD_plots_18089010.pdf
27	18089013	99(-8)	115(8)	99(-8)	115(8)	56	c=8, b=9	EPD_plots_18089013.pdf

Root files for above runs are here: rcasxx:/gpfs01/star/subsysg/EPD/sprastar/EPDHists

Overlay plot of run 18078043, 18078044, 18078045, 18078046 is available here:https://online.star.bnl.gov/epd/TimingScan/OverlayPlot.pdf
In this plot I compare

QT32c prepost =0 Gate (STAR,STOP) = (0,16) Gate (STAR,STOP) = (4,20)

vs.

QT32b Prepost=-1 Gate (STAR,STOP) = (0,16) Gate (STAR,STOP) = (4,20) Gate (STAR,STOP) = (8,24) Gate (STAR,STOP) = (12,28)

Run 18090046 has new Tier1 file = trg_170329
Here is the analysis: https://online.star.bnl.gov/epd/TimingScan/EPD_plots_18090046.pdf

e-scope traces

E-Scope connections

03/24/2017
CH#1 => PP4_tile_1 (no-split, 50 ohm)
CH#3 => QT32b board 0x18 gate
Please see attaced image:PP_6_tile_1_nosplit.pdf, which shows a cosmic ray pules and QT gate.

04/03/2017
Following scope traces are acquired during beamin in RHIC.
THreshold = 8mV
CH#1 of scop to PP6 Tile 1 no split, 50 ohm termination)
CH#3 => QT32b board 0x10 gate
Please see

04/04/2017
Following scope traces are acquired during beamin in RHIC.
THreshold = 4mV
CH#1 of scop to PP6 Tile 1 no split, 50 ohm termination)
CH#3 => QT32b board 0x10 gate
Please see https://drupal.star.bnl.gov/STAR/system/files/scopetracesPP6T1_nosplit_4mV.pdf

04/04/2017
Following scope traces are acquired during beamin in RHIC.
THreshold = 4mV && persistent

CH#1 of scop to PP6 Tile 1 no split, 50 ohm termination)
CH#3 => QT32b board 0x10 gate
Please see  : https://drupal.star.bnl.gov/STAR/system/files/scopetracesPP6T1_nosplit_4mV_persistent.pdf