BMC Cosmic Ray Test StandUpdate, Dec. 2001, Steve Ahlen - Boston Univ.

• Gas system installed on Mod-0 (EIL-1) January 2001

• Initial electrical tests January - March 2001

• DAQ set up and debugged April - May 2001

• Data taking on cosmic rays June - August 2001

• Data analysis September - October 2001

BMC Test Stand

concrete

Mod-0scintillators phototubes

XP-2020

Mod-0 (EIL-1) on combs in clean room

Cosmic Ray Test Stand

Mod-0 on Test Stand

X

Y

Z

V1

mu102201a_g

tdc100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500

100

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800

mu070201a_c

tdc100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500

200

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600

800

1000

mu102401a_h

tdc100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500

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600

800

1000

Threshold = 60 mV flow = 100 sccm

Threshold = 44 mV flow = 100 sccm

Threshold = 44 mV, flow = 500 sccm for 2 days

More timing corrections• Transit time along wire• Time of flight• Trigger time variations due to cable/electronics

variations for bottom scintillator layer

Previous corrections

• TDC card initialization offsets (12.5 ns)

• Clock (synchronization of scintillator and drift tubes)

• Transit of light along bottom scintillator

Exact tdc vs r for special cases

TDC

403

403

403

403

r(mm)

7.509

14.379

7.509

0.639

r(mm)

7.509

7.509

7.509

7.509

TDC

403

1050

403

159

0

2

4

6

8

10

12

14

16

0 200 400 600 800 1000 1200 1400

tdc channel

imp

ac

t p

ara

me

ter

r 2nd

exact

Time to distance function with correction factor

15 minutes data from mu062801a

Old Track Fitting• Multilayer (4-tube) fits

– determine the most likely position of the trajectory relative to the drift tube wire (i.e. left or right)

– consider all 16 possibilities for each multilayer

– least squares straight line fit obtained for each possibility

– the fit with the smallest rms residual is kept

• Global 8-tube fit

– use left/right information from multilayer fits

– least squares 8-tube fit

• Global 6-tube fit

– reject two most poorly fit tubes from 8-tube fit (eliminates some delta rays, multiple scatters, small impact parameter fluctuations)

– least squares fit with remaining 6 tubes

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Z

V1

0

5

10

15

20

25

30

0 100 200 300 400 500

multilayer fit (microns)

the

ta r

ms

(mra

d)

mu070201a_f; theta < 100 mrad

rms multiple scattering angle = 3.5 mrad

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1

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3

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6

0 200 400 600 800 1000 1200

xwire(mm)

rms

(mra

d)

mu070201a_f; ML fit rms < 80 microns; theta < 100 mrad

multiple scattering angle larger near beams

-0.499 - -0.494 -0.254 - -0.249 -0.004 - 0.002 0.242 - 0.247 0.491 - 0.497

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5000

6000

7000

8000

9000

mu062901a_f; no scintillator cuts

Residuals (mm)

FWHM*1.22/2.35 = 67 microns, MS cut (4 mrad)

mu062901a_f; no scintillator cuts; 97.5% of events

Residuals (mm)

FWHM*1.22/2.35 = 74 microns, no MS cut

-0.997 - -0.987 -0.496 - -0.486 -0.005 - 0.005 0.496 - 0.506 0.997 - 1.007

10000

20000

30000

Resolution Study• Use improved time-to-space function:

– add correction for large impact parameter– add corrections for layer-layer variation

• Select layer not used for track fit

• Best of 128 possibilities for 7 other layers

• Reject worst tube

• Best of 64 possibilities for 6 layers

• Compare fit position with excluded layer’s impact parameter

-10

-5

0

5

10

15

0 2 4 6 8 10 12 14 16

mu070201a_f

Impact parameter (mm)

Residuals (mm) for layer 3 - 5% delta rays

impm6

-1

-0.5

0

0.5

1

0 2 4 6 8 10 12 14

mu070201a_f

Impact parameter (mm)

Residuals (mm) for layer 3 (res study)

mu070201a_aj; m6:-.01-.01; chi6<60mic; imp:6.5-9.5mm

Residual (mm)

Residuals for layer 3: FWHM/2.35 = 85 microns

-0.991 - -0.971 -0.492 - -0.472 -0.013 - 0.007 0.486 - 0.506 0.985 - 1.005

100

200