Ronen Ingbir

Ronen Ingbir

Collaboration High precision design

Tel Aviv University HEP Experimental Group

Krakow2006

Eve

nts

(rad)

CollaborationHigh precision design Krakow2006

Energy (GeV)E

vent

s

Bhabha Scattering


Collaboration

High precision design Krakow2006

Bhabha Scattering

Head-on

(rad) X (cm)

Y (

cm)

Eve

nts


Collaboration


(rad) X (cm)

Y (

cm)

Eve

nts

Bhabha Scattering

20mrad X-angle

Detector axis


Collaboration


(rad) X (cm)

Y (

cm)

Eve

nts

Bhabha Scattering

20mrad X-angle

Outgoing beam


Collaboration


(rad)

X (cm)

Y (

cm)

Eve

nts

(rad)E

vent

s

X (cm)

Y (

cm)

Outgoing beam flat azimuthal distribution


N1 : Reconstructed and generated in acceptance region.

N2 : Generated in acceptance region but reconstructed outside.

N3 : Generated outside acceptance region but reconstructed inside.

CollaborationHigh precision design

21

23rec

NN

NN

N

NN

N

N

L

L

gen

gen

2

21

2221

2231

2223 321

NN

NNNNNN

L

L NNN

Luminosity precision determination

Krakow2006 Tel Aviv University HEP Experimental Group

Collaboration


No

Yes

Counting Bhabha events

MinMax

R~10 cm~25 cm

θ33 mrad80 mrad


Collaboration


Headon, 14,20 mrad X-angle outgoing beam

14 mrad X-angle detector axis



Collaboration





Δz


Collaboration

High precision design Krakow2006 Tel Aviv University HEP Experimental Group

Δr

ΔzΔz

Δr

Bhabha Scattering

Outgoing beam

dL/L = 10-4

0

0.0020.004

0.006

0.0080.01

0.012

0.0140.016

0.018

0.0E+001.5E-043.0E-044.5E-046.0E-04

dr (cm)

dz

(cm

)

ΔL/L=10-4

Collaboration






Collaboration






Collaboration


1. Bhabha events sample will not be pure (background).

2. Magnetic field changes the distribution (could be a dramatic effect if not aligned with the outgoing beam).

3. Event position and energy reconstruction is not perfect.

4. To evaluate the real error on luminosity one should apply MC – DATA corrections.

Are these numbers realistic ?


X- angle background

CollaborationHigh precision design

Christian Grah, DESY-Zuethen

Beamstrahlung pair background

0.E+00

1.E+09

2.E+09

3.E+09

4.E+09

5.E+09

6.E+09

8 9 10 11 12 13 14 15 16

R min (cm)

Num

ber

of B

habh

a ev

ents

per

ye

ar

0

500

1000

1500

2000

2500

3000

3500

Bac

kgro

und

(GeV

)

Events per year

Background (GeV)

250 GeV


20 mrad, DID

20 mrad, anti DID

Collaboration


Magnetic field along the outgoing beam

),,,,( EnergyBzByBx


Fast detector simulation – bias

min

*2

L

L

Changing the bias with a fixed resolution.



Changing the detector resolution with no bias


Fast detector simulation – resolution


Collaboration


How does the LumiCal performancecontribute to the detector

displacements?


Collaboration


Adding detector performance

Using bias and resolution of Pad design LumiCal

without

Including

Collaboration


Adding detector performance

Using bias and resolution of Pad design LumiCal

without

Including

Data and MCIn real life we can include the detector performance (which is measured in test beam) into MC. The only question is: How well should we know the detector performance ?



Collaboration


Test case: 20 mrad X-angle, LumiCal sits on detector axis

Unknown beam offset (amount, angle)

Simulation includes detector radius resolution and bias (Pad LumiCal)

Other parameters known

What will be the error on luminosity after using MC to correct DATA ?

Exercise


Collaboration


N1

N2

N3

N4

X (cm)

Y (

cm)

20mrad X-angle Detector axis

Collaboration


Eve

nts

(up

– do

wn)

Events (right – left)

1 mm beam shift

0.5 mm beam shift

0.3 mm beam shift

Calibration

y = 5E-05x + 0.0008

0

0.02

0.04

0.06

0.08

0.1

0.12

05001000150020002500

Events

Bea

m s

hif

t (c

m)

“Beam position”

Collaboration


20mrad X-angle Detector axis

Before correction

after correction

ΔL/L~10-2

ΔL/L~10-3

But !!!!!!

This is assuming knowing in perfect

precision many parameters

Events per year

0.E+00

1.E+09

2.E+09

3.E+09

4.E+09

5.E+09

6.E+09

8 9 10 11 12 13 14 15 16

R min (cm)

Bha

bha

even

ts p

er y

ear



Collaboration

High precision design

Summary

Krakow2006

Our recommendation

at ECFA2005 still holds


Collaboration


Beam hole

BeamCal

rmin=1.5 cm

rmax=10 cm

LumiCal

rmin=8 cm

rmax=28 cm

Head-on design

Overlap region


Collaboration


X- angle design (step 1)

Beam hole

BeamCal

rmin=2 cm

rmax=16 cm

LumiCal

rmin=13 cm

rmax=28 cm

(Reasonable Statistics)


Collaboration


BeamCal

+ 30o blind area

(incoming beam)

Detectors are centered around the

outgoing beam

X- angle design (step-2)


Collaboration


http://alzt.tau.ac.il/~ronen/

Username: ronen

Password : msc

Documents

Ronen Ingbir