Collimator Studies

• z location revisited

• new field map

• preliminary tilt studies

• some target boiling results

collimator z-location

back in January we were discussing the collimator design and thebackgrounds

Roger suggested trying to make the lower edge of the collimator definedin the most upstream collimator

this would help eliminate the lower edge of the “VT row 20” acceptance defining collimator as a large source of background

turns out that the hit we take because of finite target effects is just too big

collimator z-location

“VT row 20” try to define lower edge upstream

collimator z-location

Version original VT row 20

lower edge upstream

Rate

(MHz/octant)

813 638

<Q2>

(GeV2/c2)

.02611 .02740

Error on Qweak 4.27 4.55

bkgd from ep γ (%)

0.203

+/-.005

0.161

+/-.005

bkgd from mol e- (%)

1.369

+/-.151

2.828

+/-.152

bkgd from mol γ (%)

0.664

+/-.044

0.502

+/-.029

new field map

Compare Q2 distributions for old map (black), new map (red), BFIL 1.00

in April, Jim posted a new field map produced by Peiqing Wang and Willie Falk

the map was based on the “as manufactured” coils, which means that it is not identical in alloctants

Jim had tested the map and noticed that the focus wasn’t as good as with the old map, butit still fit on the bar

as I began testing my implementation of the new map, I discovered some problems with the read-in code having to do with the arrays

should be okay now!

new field map

“VT row 20” with BFIL 1.00 “25cm upstream” with BFIL 1.00

new map comparisonserror on Qweak vs. lower x

4.25

4.30

4.35

4.40

4.45

4.50

4.55

4.60

305 310 315 320 325 330

lower x (cm)

erro

r o

n Q

wea

k (%

) BFIL = 1.00

BFIL = 1.02

BFIL = 1.04

BFIL = 1.00 (old)

Rate vs. lower x

670

690

710

730

750

770

790

810

830

305 310 315 320 325 330

lower x (cm)

erro

r o

n Q

wea

k (%

) BFIL = 1.00

BFIL = 1.02

BFIL = 1.04

BFIL = 1.00 (old)

<Q2> vs. lower x

0.0250

0.0252

0.0254

0.0256

0.0258

0.0260

0.0262

0.0264

0.0266

0.0268

305 310 315 320 325 330

lower x (cm)

erro

r o

n Q

wea

k (%

) BFIL = 1.00

BFIL = 1.02

BFIL = 1.04

BFIL = 1.00 (old)

inelastic % vs. lower x

-0.01

0.09

0.19

0.29

0.39

0.49

0.59

0.69

0.79

0.89

305 310 315 320 325 330

lower x (cm)

erro

r o

n Q

wea

k (%

) BFIL = 1.00

BFIL = 1.02

BFIL = 1.04

BFIL = 1.00 (old)

new map comparisons

Old map, BFIL 1.00. New map, BFIL 1.00. New map, BFIL 1.04.

Blue – Elastic electronsRed – Inelastic Electrons

new map comparisons

VersionGlobal

MediumField map /

BFIL / RRate

(MHz)

<Q2>

(GeV2/c2)error on

Qweak (%)inelastic %

(w/ x10 factor)

original VT heliumold /

1.00 / 313875 .0261 4.18 .086

original VT airold /

1.00 / 313822 .0262 4.26 .076

25 cm upstream

airold /

1.00 / 313798 .02572 4.32 .056

25 cm upstream

airnew /

1.00 / 315811 .02571 4.30 .039

25 cm upstream

airnew /

1.02 / 318814 .02569 4.29 .068

25 cm upstream

airnew /

1.04 / 320807 .02579 4.30 .066

collimator tilt studies

removed “cleanup” collimators

no beamline, new map BFIL 1.00

did not move the quartz bar (lower edge 315cm)

for pitch, roll and yaw ±5º

for x, z ±5 cm

Also assumed all plots were linear, though some obviously aren’t

collimator tilt studies

<Q4> as a function of shift

4.00E-04

5.00E-04

6.00E-04

7.00E-04

8.00E-04

9.00E-04

1.00E-03

1.10E-03

1.20E-03

-6 -4 -2 0 2 4 6

shift (cm or degrees)

<Q4>

Roll (degrees)

Yaw (degrees)

Pitch (degrees)

x (cm)

z (cm)

Rate as a function of shift

400

500

600

700

800

900

1000

1100

1200

1300

-6 -4 -2 0 2 4 6

shift (cm or degrees)

Rat

e (M

Hz/

oct

ant)

Roll (degrees)

Yaw (degrees)

Pitch (degrees)

x (cm)

z (cm)

<Q2> as a function of shift

1.90E-02

2.10E-02

2.30E-02

2.50E-02

2.70E-02

2.90E-02

3.10E-02

3.30E-02

-6 -4 -2 0 2 4 6

shift (cm or degrees)

<Q2> Roll (degrees)

Yaw (degrees)

Pitch (degrees)

x (cm)

z (cm)

par 

roll (º) -0.0275 -0.0039 -0.0096

yaw (º) -0.0161 -0.0008 0.0014

pitch (º) -0.0005 0.0039 0.0001

x (cm) -0.0993 0.0505 0.0956

z (cm) 0.0077 -0.0078 -0.0137

par

Q

Q 2

2

1

par

R

R 1

par

Q

Q 4

4

1

Qweak beam tests

performed March 26th , 27th

target boiling studies

low current tests (see Mark’s talk)

beam current monitoring (Dave Mack)

Thanks to everyone who took shifts!

target boiling studies

target boiling studies30 Hz LUMI widths vs. Current

LH2, 8Hz fan, 1.2x1.2 raster

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20 25 30 35

Current (uA)

LU

MI w

idth

(p

pm

)

LUMI1

LUMI2

LUMI3

LUMI5

LUMI6

LUMI7

LUMI8

30 Hz LUMI widths vs. CurrentLH2, 40Hz fan, 1.8x1.8 raster

0

100

200

300

400

500

600

700

0 5 10 15 20 25 30

Current (uA)

LU

MI w

idth

(p

pm

)

LUMI1

LUMI2

LUMI3

LUMI5

LUMI6

LUMI7

LUMI8

250 Hz LUMI widths vs. CurrentLH2, 8Hz fan, 1.2x1.2 raster

0

2000

4000

6000

8000

10000

12000

14000

0 5 10 15 20 25 30

Current (uA)

LU

MI w

idth

(p

pm

)

LUMI1

LUMI2

LUMI3

LUMI5

LUMI6

LUMI7

LUMI8

250 Hz LUMI widths vs. CurrentC, 8Hz fan, 1.2x1.2 raster

0

5000

10000

15000

20000

25000

0 5 10 15 20 25 30

Current (uA)

LU

MI w

idth

(p

pm

)LUMI1, C

LUMI2, C

LUMI3, C

LUMI5, C

LUMI6, C

LUMI7, C

LUMI8, C

250 Hz LUMI widths vs. CurrentLH2, 40Hz fan, 1.8x1.8 raster

0

2000

4000

6000

8000

10000

12000

0 5 10 15 20 25

Current (uA)

LU

MI w

idth

(p

pm

)

LUMI1

LUMI2

LUMI3

LUMI5

LUMI6

LUMI7

LUMI8

30 Hz LUMI widths vs. CurrentC, 8Hz fan, 1.2x1.2 raster

0

200

400

600

800

1000

1200

1400

1600

1800

0 5 10 15 20 25 30

Current (uA)

LU

MI w

idth

(p

pm

)

LUMI1, C

LUMI2, C

LUMI3, C

LUMI5, C

LUMI6, C

LUMI7, C

LUMI8, C

target boiling studies

30 Hz, 8Hz fan, 1.2x1.2 raster, C 30 Hz, 8Hz fan, 1.2x1.2 raster, C

250 Hz, 8Hz fan, 1.2x1.2 raster, C 250 Hz, 8Hz fan, 1.2x1.2 raster, C