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

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

200

300

400

500

600

700

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

400

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

200

400

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

X

Y

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

0

1

2

3

4

5

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

1000

2000

3000

4000

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