Beam Monitoring from Beam Strahlung

new work by summer students

Magdalena Luz (HU)

Regina Kwee (HU)

Achim Stahl DESY Zeuthen 10.Oct.2003

LumiCal

BeamCal

Beam StrahlungTESLA: small bunches (5nm x 550nm x 300μm)

huge electric/magnetic fields

Beam StrahlungParticles accelerated by electric field

creation of photon radiation (beamstrahlung)

Simulation of collisions by guinea-pig

Beam StrahlungCreation of e+e- pairs by photon-photon interactions

(2nd order effect, e+e- << s)

Simulation of collisions by guinea-pig

Beam StrahlungTracking of particles into the forward region

(e+e- confined by magnetic field of detector)

Tracking by simple stand-alone program

Beam StrahlungCreation of signals in detectors (LCal + Collimators?)

fast diagnosis + offline analysis

Over-simplified detector simulation

• detectors subdivided into cells

• sum energy impact on cells

3 potential sources of information

• energy-distribution of pairs

• number-distribution of pairs

• distribution of photons

Current Analysis Concept

Beam Parameters• determine collision

• creation of beamstr.• creation of e+e- pairs

guinea-pig

Observables• characterize energy

distributions in detectors

analysis program

1st order Taylor-Exp.

Observables

Observables

Δ B

eamP

ar

Taylor

Matrix

nom

= + *Solve by matrix inversion(Moore-Penrose Inverse)

Example: Observables

total energy first radial moment direction of thrust axis thrust value (A + D) – (B + C) (A + B) – (C + D) (A + C) – (B + D)

A

BC

D

Example: Slopes

beam parameter i

obs

erv

ab

le j

1 point =1 bunch crossing

by guinea-pigparametrization

(polynomial)

slope at nom. value taylor coefficient i,j

Analysis Problems I

at nominal valuesimulate 10 bunch crossings calculate spread

assume same errorfor all points

((A

+C

) –

(B+

D))

/ t

otal

ene

rgy

Analysis Problems II

bunch rotation in mrad

tota

l ene

rgy

slope = 0at nom. Parameter

linear approximation fails

true for all observables analysis fails

1st Results: Single Parameter Analysis

nominal our precision Beam Diag.

Bunch width x Ave.

Diff.

553 nm 1.2 nm

2.8 nm

~ 10 %

~ 10 %

Bunch width y Ave.

Diff.

5.0 nm 0.1 nm

0.1 nm

Shintake

Monitor

Bunch length z Ave.

Diff.

300 μm 4.3 μm

2.6 μm

~ 10 %

~ 10 %

Emittance in x Ave.

Diff.

10.0 mm mrad 1.0 mm mrad

0.4 mm mrad

?

?

Emittance in y Ave.

Diff.

0.03 mm mrad 0.001 mm mrad

0.001 mm mrad

?

?

Beam offset in x

Beam offset in y

0

0

7 nm

0.2 nm

5 nm

0.1 nm

Horizontal waist shift

Vertical waist shift

0 μm

360 μm

80 μm

20 μm

None

None

1st Results: Two Parameter Analysis

Exa

mpl

e: v

ertic

al w

aist

shi

ft

Sn

gl P

ara

m R

eso

: 20

μm

Next Steps:

Fix analysis problems

6-parameter fit

Test on realistic beam simulation

approach machine people

New Directions: What can we learn from the photons ?

Think about hardware implementation

Any consequences on detector design ?

First Look at Photons

First Look at Photons

nominal setting(550 nm x 5 nm)

σx = 650 nmσy = 3 nm

Next Steps:

Fix analysis problems

6-parameter fit

Test on realistic beam simulation

New Directions: What can we learn from the photons ?

Think about hardware implementation

Any consequences on detector design ?