u.s. fcal efforts

FCAL Munich October 17 2006 W.M. Morse

1

U.S. FCAL Efforts

William Morse - BNL


2

U.S. Interests

• BNL – BeamCal, GamCal

• Yale – GamCal

• Colorado – SUSY studies

• Morse is the SiD forward coordinator

• Have submitted GamCal R&D Proposal to DOE

• Preparing BeamCal R&D Proposal to DOE


3

U.S. Interests

• BNL PI: W. Morse• F. Lanni, D. Lissauer: BeamCal readout issues• Z. Li: radiation damage issues• B. Parker: machine interface issues• Yale PI: M. Zeller• G. Atoian, V. Issakov, A. Poblaguev: GamCal

design issues• Colorado PI: U. Nauenberg: SUSY studies


4

BeamCal Radiation Damage

• 10MGy/yr from electrons

• 21014 n/cm2 per yr, mainly from giant dipole resonance (10-40 MeV NnN*)

• Zheng Li (BNL Instrumentation) recommends high resistivity MCZ Si cooled to -10C


5

SiD 14mr with anti-solenoid


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SiD Anti-Solenoid Magnet• Brett Parker (BNL) design – see VLCW06 talk• Lower B affects pairs and also backsplash to vertex detector

0

1

2

3

4

5

0 0.5 1 1.5 2 2.5 3 3.5

z (m)

B_z

(T)

PT = 0.02 GeV/c, PL = 0.25 GeV/c

-0.02

-0.01

0

0.01

0.02

0 0.01 0.02 0.03 0.04

hor (m)

vert

(m)


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Fast Feedback

• The ILC fast feedback team requests a signal at 3MHz with low latency almost proportional to actual luminosity for fast optimization

• Comprehensive info at 5Hz to a data base (still to be defined) P.N. Burrows GDE/MDI Vancouver 19/7/06

Intra-train y + y’ IP feedback simulations

0 100 200 300 400 500 6000

1

2

3x 10

34

Bunch #Lu

mino

sity /

cm-2

s-1

y position FB:

restore collisions

within 100 bunches1 seed:

post-BBA

+ GM

+ wakes

y position scan:

optimise signal

in pair monitor

y angle scan

OPTIMAL

LUMINOSITY


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Achieving the Design Luminosity Will Be a Challenge

• Bunch P- (t) {N, E, x, y, z, x, y, z, xy, x, y}

• Bunch P+(t) {N, E, x, y, z, x, y, z, xy, x, y}

• Instantaneous Luminosity:

oy

ox

oo NNtL

4)(

x

y


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Run Time Measurements

• Beam-beam deflections (pickup electrodes)

• Beam-strahlung gammas (GamCal)

• Beam-strahlung pairs (BeamCal)

• We need robust and complementary information


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Beam-strahlung• F = e(E + cB). Bmax 1KT• Instantaneous power radiated:• P 3% Pe N 1.5Ne

• Bethe-Heitler: e → e e+e-

BH 38 mb• <E> 1GeV• Landau-Lifshitz: ee → ee e+e-

LL 19 mb• <E> 0.15GeV• Other processes much smaller• C. Rimbault et al., Phys Rev ST AB 9,034402 (2006).

mc

FrP

3

2 220


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Bethe-Heitler Pairs

e → e e+e-

oy

ox

oe

oBH

ee

NNN

oy

ox

oeBHee N

N

N

oy

ox

oeee N

E

E

For left and right detectors separately: N+/xy and N-/xy. Question: How well does this really work? Answer: Needs simulation.


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Landau-Lifshitz Pairs

• ee → eee+e-

oy

ox

ooLLLL

ee

NNN

For left and right detectorequally

1 GeV


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Simulations

• W. Morse (BNL)

• W. Lohman, E. von Oelson, and M. Ohlerich (DESY Zeuthen)

• To Be Submitted as an ILC Note

• Guinea Pig simulations varying some of the 500 GeV ILC bunch parameters around nominal values


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Vertical offset

0

50

100

150

200

-200 -100 0 100 200

offset/2 (nm)

ener

gy

in g

amm

as (

MT

eV)

0

5

10

gammas

pairs

E BeamCal (TeV)


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Vertical Offset

0

5

10

15

20

-200 -150 -100 -50 0 50 100 150 200

offset/2 (nm)

Lu

min

osi

ty (

10^

33 c

m^

-2/s

)

0

0.05

0.1

Lum

R

R (10-6)


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Bunch Width

0

100

200

300

400

500

600

400 500 600 700 800 900

Bunch width (nm)

Energ

y in g

amma

s (MT

eV)O

0

10

20

30

40

50

60

gammas

pairs

0

5

10

15

20

25

30

400 500 600 700 800 900

Bunch width (nm)

Lumi

nosit

y (10

^33 c

m^-2/

s)0

0.02

0.04

0.06

0.08

0.1

0.12

Lum

R

BeamCal E (TeV)

R 10-6


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Comparison• Sign of dE/d(bunch characteristic) at design values. Note that all five

lines are different, which means complementary information.

Parameter Pairs Gammas Ratio

X offset 0 (max) 0 (max) 0 (max)

z - - 0

y0 (max) 0 0 (max)

x - - -Y offset 0 (max) 0 (min) 0 (max)


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Bunch Height

0

40

80

120

160

200

240

3 5 7 9 11

Bunch height (nm)

Energ

y in g

amma

s (MT

eV)

0

4

8

12

16

gammas

pairs

0

2

46

8

10

1214

16

18

3 5 7 9 11

Bunch height (nm)

Lum

inos

ity (1

0^33

cm^-

2/s)

0

0.02

0.04

0.06

0.08

Lum

R


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Bunch Length

0

50

100

150

200

250

300

350

150 200 250 300 350 400

Bunch Length (um)

gam

ma e

nerg

y (MT

eV)

0

5

10

15

20

25

gammas

pairs

0

2

46

8

10

1214

16

18

150 200 250 300 350 400

Bunch length (um)

Lum

(10^

33 cm

^-2/s

)0

0.02

0.04

0.06

0.08

Lum

R


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Is There More Info in BeamCal?

• T.Tauchi,K.Yokoya• Phys Rev E51,6119(95)• 6<r<7cm azimuthal dist• But, Moliere dia. 2cm!• Also, 1 Bhabha/BX!• Thus we need more

simulation to show that it is robust enough.

normalized

0.001

0.01

0.1

0 1.57 3.14

theta (radians)

1/E

dE

/ds

(0.8

cm)^

-1

sig_y

2sig_y


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Robust and Complementary

Detector X offset Y offset x y

PUE x y Normal Normal

E GamCal Low High Low Normal

E BeamCal Low Low Low Low

Luminosity, ie. R, is low. Note that all columns are different, ie. complementary information.


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Large Crossing Angle GamCal

0

0.2

0.4

0.6

-0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

z(m)

x(m

)

Gas jet followed by a 1m long 1.5T dipole magnetic field. Trajectories of positrons of momentum 0.1, 1, and 10 GeV/c are shown.


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GamCal Backgrounds

Gammas

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

-2 -1 0 1 2

log(E)

dN/d

log(

E)

Beamst

Brem

1

10

100

1000

-2 -1 0 1 2

log(E)

dN/d

log(

E)

Delta Rays

Beamst e


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Conclusions

• We need robust, redundant information:

• Beam-beam deflections

• Beam-strahlung gammas

• Beam-strahlung pairs

• E(pairs)/E(gammas) particularly valuable

• Largely proportional to instantaneous luminosity


25

Extra Slides


26

1 2

0

21

y

E

0

21

y

B

+ -

0

221

212

01

2

eyey

F

y

z


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Perfect Collisions

zx

NE

2

2

zyx

ee

NE

3

3

u.s. fcal efforts

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