LHCb VELO Testbeam at Fermilab Jianchun Wang Syracuse University.
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LHCb VELO Testbeam at Fermilab Jianchun Wang Syracuse University
Jianchun Wang2 Track Data Format C: Pixel Track Event for VELO 1.Magic cookie (01 02 03 04)I*4 2.Length of the blockI*4 3.Block type (7)I*4 4.Trigger event IDI*4 5.Matched VELO event IDI*4 6.Distance from trigger jumpI*4 7.Number of tracksI*4 8.Number of hits (Track 1)I*4 9.Chi2 of fitF*4 10.Projected X at DUTF*4 11.Projected Y at DUTF*4 12.Track slope XF*4 13.Track slope YF*4 14.Projected X error at DUTF*4 15.Projected Y error at DUTF*4 16.… ( Track 2) 17.FF FF FF 00I*4 A: Raw Track 1.Magic cookie (01 02 03 04)I*4 2.Length of the blockI*4 3.Block type (6)I*4 4.Number of hitsI*4 5.Tbdb ID ( Hit 1)I*4 6.Chip IDI*4 7.Local XF*4 8.Local YF*4 9.Expected X resolutionF*4 10.Expected Y resolutionF*4 11.… (Hit 2) 12.FF FF FF 00I*4 B: VELO Alignment 1.Magic cookie (01 02 03 04)I*4 2.Length of the blockI*4 3.Block type (8)I*4 4.Number of VELO sensorsI*4 5.X offset of sensor 1F*4 6.Y offset of sensor 1F*4 7.Angle around X axis of sensor 1F*4 8.Angle around Y axis of sensor 1F*4 9.Angle around Z axis of sensor 1F*4 10.… 11.FF FF FF 00I*4 For pixel alignment:AAAAAA… For VELO study:BCCCCC…
Jianchun Wang3 Event Matching Between Pixel and VELO There are fake trigger or trigger inefficiency, that are different in the two systems. Showing up in data ~ few counts difference over the whole run (~50K triggers). To determine and correct this trigger jump we rely on matching between VELO hit and pixel track. Out of 115 runs 81 have this problem, totals 349 jumps. For some studies events around the jump should be excluded. Accu. Number of VELO Hits Trigger Count Offset Best match Offset pix_090420_111844
Jianchun Wang4 Pixel Trigger Issue The pixel trigger ID should be continuously incremented number starting from 0. 15 files with pixel trigger issues that the trigger number are not continuous. In 3 runs, few trigger pockets were not sent out, resulting a jump of one count or few. This does not affect event matching between pixel and Velo systems. In 13 runs, there were fake trigger pockets sent out (total 63 times). Because the trigger counter has cycle of 4096. Count smaller than in the previous event results in an increment of 4096. This was corrected manually. Run pix_090420_094446 Pixel Trigger ID (100 bins) Before After
Jianchun Wang5 Summary Of Status Pixel and VELO events are matched in all runs. Wrongly assembled VELO events are fixed. We need to regenerate date files of these runs. Pixel alignment is good enough for many studies. More precise alignment is on the way. Tracks of reasonable alignment are generated. Tool is written to handle tracks. Noise, efficiency, resolution, and TELL1 algorithm cross-checking are on-going.
Jianchun Wang7 Residual On the 5 th Station Measurement – Track Projection (mm) Number of Entries (Arb. Unit) Ncol > 1 Nrow > 1 Ncol = 1 Nrow = 1 Different Scale Resolution ( m) Residual Remove track Ncol > 17.65.8 Ncol = 1120.0119.8 Nrow > 18.36.6 Nrow = 112.711.7 Binary readout 5 pixel stations Simulated through iterations track proj. error ~ 4.9 m
Jianchun Wang8 Track Probability Issue Simulation parameters N RowN Col 1>11 Probability0.7590.2410.9780.022 Resol ( m) 11.76.6119.85.8 TypeZ (mm)X (10 -3 X 0 ) X-pixel-4509.5 Y-pixel-4449.5 VELO06.4 Y-pixel31712.5 X-pixel5149.5 Y-pixel5209.5 Non-gaussian Prob ( 2, ndof) Tracks (arb. Unit) Exclude Ncol = 1 With multiple scattering Prob ( 2, ndof) Tracks (arb. Unit) Expect Seen Uniform dist for Ncol=1 Gaussian for the rest
Jianchun Wang9 Tracking Error Multiple scatt. Include Ncol=1 Residual ( m) xx yy 5 stations No 7.476.32 NoYes7.426.30 YesNo7.736.53 Yes 7.696.51 Multi-ccatt. only2.071.74 4 stations YesNo7.717.72 Yes 7.68 Multi-scatt. only1.85 5 pixel stations Tracking Error from Pixel ( m) Y X Log ( number of tracks ) Calculated without multiple scattering Multiple scattering contributes 1.7-2.1 m to track projection error. One can select events of better tracking error. Measurements of Ncol=1 improve track projection precision, although distort the track probability distribution.
Jianchun Wang10 Look at R/ Data X ( mm) Y ( mm) Effective Track Angle (degree) Signal (ADC) Matched Hits We took data at nominal 0, 4, 8, 12 degrees rotated around horizontal axis. The effective angle is smaller due to concentric strips. Pixel coverage
Jianchun Wang11 Effective Track Angle (Degree) Percentage of Hits Charge Sharing (I) Cluster Size All pitches & track angle Seed threshold = 6 ADC ~ 9.6 Ke Side threshold = 3 ADC ~ 4.8 Ke Strip pitch (40, 50) m N strip = 1 N strip = 2 N strip = 3 R sensor of R/ pair Range: angle 0.5
Jianchun Wang12 Charge Sharing (II) Pitch ( m) 40 – 50 50 – 60 60 – 70 70 – 80 80 – 90 90 – 100 Effective Track Angle (Degree) (N strip > 1) / N total (%) R/ data is split into 1 of angle & 10 m of pitch sub-samples. Sub-samples of 0 , 3 , 7 and 11 are with reasonable large statistics. Strip Pitch ( m) (N strip > 1) / N total (%) Angle ( ) -0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5
Jianchun Wang13 Velo Resolution Measurement <Resid = 19.2 m trk > = 8.0 m N event = 175K R velo – R track ( m) Resid = 18.0 m trk > = 5.1 m N event = 12.5K R velo – R track ( m) Trk error = (pixel) 1.85 m (multi-scatt.) = quadratic average over all trks Tracking Error from Pixel ( m) Error < 6 m To improve tracking precision one has to sacrifice statistics.
Jianchun Wang14 Resolution vs Pitch R sensor of R/ pair Velo Hit Resolution ( m) Preliminary !. Angle ( ) - 0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5 Strip Pitch ( m) Seed threshold = 6 ADC ~ 9.6 Ke Side threshold = 3 ADC ~ 4.8 Ke Tracking projection uncertainty removed from resolution. Tracking precision is determined for each point ( ~ 4.7–5.4 m). Error bar represents only statistic error. Linear charge weighting, eta- correction not applied yet.
Jianchun Wang15 Tracking Precision For each track the projections on Velo and projected errors in both X and Y directions are calculated using the corresponding pixel resolutions. R and error in R is calculated from X/Y. For each sample (point), the projection error is quadratically averaged over all tracks used. Projection error due to multiple scattering is ~1.85 m obtained from simulation. The alignment error is to be determined. Angle ( ) - 0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5 R Error From Track Projection ( m) Strip Pitch ( m)
Jianchun Wang16 Resolution vs Track Angle Pitch ( m) 40 – 50 50 – 60 60 – 70 70 – 80 80 – 90 90 – 100 Effective Track Angle (Degree) Velo Hit Resolution ( m) Effective track angle is determined in plane perpendicular to the strip. Sub-samples of 0 , 3 , 7 and 11 are with reasonable large statistics. Other angles are due to concentric strip, thus with small amount of hits.
Jianchun Wang17 The Eta Curve Track Hit Fraction Center of Strip N Center of Strip N+1 Only Strip N has Charge Cluster Fraction Only Strip N+1 has Charge One strip shift due to tracking precision All pitches & angles Nstrip = 1 removed
Jianchun Wang18 The Eta Curves Of Small Pitches Cluster Fraction Track Hit Fraction Angle=0 Angle=3 Angle=7 Angle=11 Pitch = (40-50) m Nstrip = 1 removed
Jianchun Wang19 The Eta Curves Of Small Pitches Cluster Fraction Track Hit Fraction Angle=0 Angle=3 Angle=7 Angle=11 Pitch = (40-50) m Cluster fraction=0 or1 correspond to nstrip=1, indicating how charge sharing varies with hit position.
Jianchun Wang20 Uniform Irradiation: 6 VELO year eq. Useful for resolution, efficiency & S/N vs pitch, angle (x-axis rotations) Uniform Irradiation: 0 VELO year eq. Useful for resolution & S/N vs pitch, angle (x- axis rotations) Varying Irradiation: 0-6 VELO year eq. Useful for resolution, efficiency & S/N vs. pitch and dose
Jianchun Wang21 RR Module: Position of irradiation spots Beam at the top 500V on each sensor Tell1 8 n-in-p Tell1 5 n-in-n Beam low irr high irr Bottom Top RR_0deg_Top_latency_0x17_delay_40ns_Kazu_ HV500 -20090427-081938.mdf RR Files used:
Jianchun Wang24 Header Height Vs V2.5 Kazu’s setting, at FNAL header height = 28.48 ± 1.48 T = 23 - 27 °C, Kazu setting T = 4 - 8 °C, Kazu setting T = ~ 2 °C, Kazu setting T = ~ 27 °C, Chris setting We tried to find out what value V2.5 was during testbeam. Obtained from one run. Uncertainty of value is about 0.1-0.2. Sigma indicates spread among 64 links. Chris’s setting, at FNAL header height = 29.34 ± 1.12 Header height is also affected by T and electronics setting, not just V2.5 alone.
Jianchun Wang25 Header Height vs Temperature V2.5 at nominal value Kazu setting H = 50.934 – 0.1754 T( C)
Transient Event Store for Emulator Jianchun Wang27 Sector ID / Array Inner stripsOuter strips comment minmaxminmax 1 Strip01706831023 (171, 341) inner & outer strips Index0170192532 2 Strip17134110241364 (171, 341) inner & outer strips Index5767467681108 3 Strip34251113651706 (170, 342) inner & outer strips Index1152132113441685 4 Strip51268217072047 (171, 341) inner & outer strips Index1728189819202260 Normal data from each hybrid are stored in an array of 2048 = 64x32 elements, indexed by either the electronics channel or the strip ID. In emulator dummy elements are added to mimic 4 FPGAs. The overall size is 2304 = (64+8)x32. Before reordering data are stored in the order of electronics channel. And 2x32 dummies are added after each 512=16x32. ( DecodedADC, SubtracedPedADCs, FIRCorrected, and ADCMCMSCorrected). The pedestal are still stored in an array of 2048 (SubtractedPed). After channel reordering data are stored in the order of strip ID. For R sensor 2x32 dummies are added after each 512 strips (16x32). For sensor each sector occupies 18x32 elements with inner strips the beginning of first 6x32 and outer strips the beginning of next 12x32 in the table (ADCReordered, ADCCMSuppressed).