Title: Calibration of the CMS Outer Hadron Calorimeter : an update
1Calibration of the CMS Outer Hadron Calorimeter
an update
- Include J/y ?µµ and ?(1S) ?µµ physics events
along with W?µn and Z/g ? µµ events - Cosmic muon events
- Correct for the missing factor of 2p for the
integration over azimuthal angle - Use spectrum from L3CGEN (Prof. Hebbekers code,
presently in CMSSW) - Take care of the solid angle coverage of double
layers in Ring-0
2Expected calibration accuracy vs Statistics
(reminder)
Uncertainty()
Uncertainty()
Uncertainty()
Ring 0 Ring 1
Ring 2
Statistics Statistics
Statistics
- 10 accuracy is possible with only 50 events in
Ring 0 and Ring 2, whereas it requires about 90
events for Ring 1 - 500 events are required for 3-4 accuracy for
all tiles
3Muon selection criteria (reminder)
- Assuming low luminosity trigger scenario
- Single muon trigger criterion PT gt 19.0 GeV
- Double muon trigger PT1,T2 gt 7.0 GeV
- Momentum threshold for calibration, PT gt 5.0 GeV
- Trigger efficiency, L1, L3 (including isolation)
69 - Contribution of Z?µµ is only 10 to that of W?µ?
and number events are negligible when event is
triggered by only endcap muon
4Expected muon (from W and Z) events in 100 pb-1
data
?/f 1 2 3 4
5 6 Average 1 548.9 678.7
619.5 636.4 624.2 507.3 602.5 2
531.0 668.2 615.8 616.0 621.6 502.4
592.5 3 524.7 657.7 643.8 646.7
622.5 496.9 598.7 4 259.4 336.1
321.5 327.1 309.5 263.6 302.9 5
470.8 554.8 544.2 529.5 513.7 471.0
514.0 6 513.3 581.4 606.9 608.7
582.4 542.2 572.5 7 483.4 553.6
551.0 566.1 544.7 489.9 531.5 8
450.1 530.1 538.5 530.9 524.9 473.7
508.0 9 425.9 508.4 520.1 501.8
503.8 452.9 485.5 10 483.2 570.1
556.7 563.4 550.1 514.6 539.7 11
483.9 569.3 560.0 549.6 543.8 489.1
532.6 12 572.6 684.0 669.9 662.0
647.0 602.0 639.6 13 581.3 696.5
679.7 662.7 639.9 591.8 642.0 14
590.6 689.5 668.5 657.3 656.9 606.3
644.8 15 288.5 357.2 336.6 321.7
339.7 303.0 324.5
Z?µµ (10) ?? µµ (6)
- Better than 4 accuracy is achievable with this
luminosity for all tiles except ?15, where it is
about 6
- Gain is only 20 by bringing down the pT
threshold to 5 GeV for these physics channels.
Not worth to have huge background.
5Muon from physics process ?(1S) ?µµ and J/? ?µµ ?
- Huge cross section ?(1S) ?µµ (s.Br 40 nb) and
J/? ?µµ (s.Br 1.3 µb) with ckin(3)4. (using
default PYTHIA6.4) - But, momentum spectrum is very soft (selected
events with PTµ gt3 GeV and ?lt2.5)
6Expected muon (from ?(1S) and J/?) events in 100
pb-1 data
?/f 1 2 3 4
5 6 Average 1 89.4
114.91 129.77 135.65 129.86 104.26
117.31 2 65.6 118.83 97.66 122.87
116.24 107.63 104.82 3 90.15 103.64
91.56 131.14 103.00 104.51 104.00 4
41.85 71.04 66.47 65.85 40.94
60.46 57.78 5 91.67 103.52 93.42
87.94 105.23 75.96 92.96 6 87.64
108.09 110.95 91.46 92.63 94.84
97.61 7 96.70 95.95 111.57 88.24
83.30 90.74 94.42 8 90.83
98.63 77.25 88.83 86.12 100.42
90.35 9 72.78 79.67 97.22 71.07
65.79 62.83 74.89 10 88.13 114.82
77.14 113.16 92.93 93.58 96.63
11 68.35 87.04 96.78 78.81 71.90
85.73 81.43 12 90.27 113.75 96.24
101.58 103.39 76.32 96.93 13 82.80
125.93 123.78 92.93 104.58 91.31
103.55 14 84.36 136.45 116.10 82.51
118.54 80.57 103.09 15 55.18 53.85
59.77 49.47 40.27 60.68 53.21
- Muon identification efficiency with trigger is
60 (need simulation for better estimation) - Contribution from ?cs and ?bs are also
included - Increase statistics by about 20 with respect to
muons from W and Z decay - Tevatron results 30 J/? from B decays expect
more at LHC
- Reduction of PT threshold to 5(6) GeV, increase
statistics by 40 (60) - But, production cross section and feed down from
B-hadron has large uncertainty
7Low energy run in year 2007
- Momentum spectra of muons from W?µn and Z?mm are
no factors for the trigger criteria, but the main
problem is the production cross section - At 900 GeV, W?µn production cross section reduces
from 65.6 nb to 1.2 nb - Similar reduction in Z?mm and onium production too
Need huge data to calibrate HO, which may not be
available
8HO calibration with cosmic muon
Cosmic ray muon spectrum and emperical formula
for PCos? gt100 GeV (PDG)
Muon flux in CMSSW
- dN/dE function of log(E)
- Angular dependency 1 a(P) cos(q), whereas in
PDG 1/cos(q) - Flux rate (Pcos(q) gt 59 GeV) 7.40 ?10-5
/cm2/s/sr (PDG) ? 5.72 ?10-5
/cm2/s/sr
9Cosmic muon flux as a function of accepted
inclination angle
- Large dependency on muon acceptance angle
- Flux intensity would be different for different
sectors (0,30,60,90 degree) due to different
solid angle coverage of cosmic muon
- Cosmic muon flux rate decreases by factor 2.4
(16) for the muon acceptance angle 70 (10) degree
from a horizontal tile to a vertical tile - Muon flux does not increase much beyond
inclination angle greater than 70o, flux rate
decreases rapidly beyond that
10Muon flux in Ring-0 tiles
- Take a point, P and surface, A on the surface of
one layer (Layer-1) - Take a small area, B (1cm x 1cm) on the surface
of the second layer (Layer-0) - Calculate solid angle coverage, W of B with
respect to P as well as the direction, q - Integrate over energy, the muon flux for that
angle, F - Muon flux passed through area A and B F WB
- Now move A to cover whole surface on Layer-1,
then Layer-0 to obtain total flux
Layer-1
A
P
Layer-0
B
11Cosmic ray muon in horizontal tiles / day
?/f 1 2 3 4
5 6 Average 1 1950.5
2747.7 2606.7 2545.7 2545.7 1872.0
2378.1 2 1954.5 2760.9 2619.1
2557.4 2557.4 1876.4 2387.6 3
1965.6 2788.3 2644.2 2581.4 2581.4
1887.0 2408.0 4 846.6 1206.1
1143.5 1116.1 1116.1 812.8 1040.2
5 4901.1 5662.0 5475.7 5398.0
5398.0 6283.2 5519.7 6 5662.0
6541.1 6325.8 6236.1 6236.1 7258.7
6376.6 7 5475.7 6325.8 6117.6
6030.9 6030.9 7019.8 6166.8 8
5398.0 6236.1 6030.9 5945.3 5945.3
6920.3 6079.3 9 5398.0 6236.1
6030.9 5945.3 5945.3 6920.3 6079.3
10 6283.2 7258.7 7019.8 6920.3
6920.3 8055.1 7076.2 11 6523.9
7536.8 7288.7 7185.4 7185.4 8363.6
7347.3 12 8465.1 9779.3 9457.5
9323.4 9323.4 10852.2 9533.5 13 9058.3
10464.7 10120.3 9976.7 9976.7 11612.7
10201.6 14 9729.2 11239.7 10869.8 10715.6
10715.6 12472.8 10957.1 15 5179.0 5983.1
5786.2 5704.2 5704.2 6639.6 5832.7
Muon acceptance angle is 70o
- 1-day is sufficient for 2 accuracy of
calibration constant
12Cosmic Ray muon in vertical tiles / day
?/f 1 2 3 4
5 6 Average 1 99.9 176.8
161.5 155.1 155.1 93.4
140.3 2 104.2 181.8 166.4
160.0 160.0 97.4 144.9 3
112.5 194.6 178.0 171.0 171.0
105.4 155.4 4 50.2 88.5
80.8 77.6 77.6 46.7
70.2 5 2062.1 2382.3 2303.9 2271.2
2271.2 2643.6 2322.4 6 2382.3 2752.1
2661.6 2623.8 2623.8 3054.1 2682.9 7
2303.9 2661.6 2574.0 2537.5 2537.5
2953.6 2594.6 8 2271.2 2623.8 2537.5
2501.5 2501.5 2911.7 2557.9 9 2271.2
2623.8 2537.5 2501.5 2501.5 2911.7
2557.9 10 2643.6 3054.1 2953.6 2911.7
2911.7 3389.1 2977.3 11 2744.9 3171.1
3066.7 3023.2 3023.2 3519.0 3091.4 12
3561.6 4114.6 3979.2 3922.8 3922.8
4566.0 4011.2 13 3811.2 4403.0 4258.1
4197.7 4197.7 4886.0 4292.3 14 4093.5
4729.1 4573.4 4508.6 4508.6 5247.9
4610.2 15 2179.1 2517.4 2434.5 2400.0
2400.0 2793.6 2454.1
Muon acceptance angle is 70o
- 5 accuracy requires at least four days of cosmic
data to calibrate Ring-0 h4
13Conclusion
- 4 accuracy in HO calibration constant is
achievable with 100 pb-1 data - Muon from ?(1S) and J/? can reduce uncertainty,
but these processes have large uncertainty in
production cross-sections - One day cosmic muon run gives much better
accuracy in Ring-1 and Ring-2, whereas for
Ring-0, ?-4, one need at least 4 days - HO calibration with cosmic muon demands muon
trigger with large inclination, large solid angle
coverage - In the year 2007, a cosmic muon calibration is
absolutely necessary, data from pp collisions
will take longer time to achieve a reasonable
accuracy, where as later on (2008 onwards), data
from pp collisions will be sufficient to
calibrate HO.
Remaining issues
- Recalculate all numbers using CMSSW (full
detector simulation)