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 Strahlung TESLA: small bunches (5nm x 550nm x 300μm) huge electric/magnetic fields

Beam Strahlung Particles accelerated by electric field  creation of photon radiation (beamstrahlung) Simulation of collisions by guinea-pig

Beam Strahlung Creation of e + e - pairs by photon-photon interactions (2 nd order effect, e + e - <<  s) Simulation of collisions by guinea-pig

Beam Strahlung Tracking of particles into the forward region (e + e - confined by magnetic field of detector) Tracking by simple stand-alone program

Beam Strahlung Creation 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 1 st order Taylor-Exp. Observables Δ BeamPar 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 observable j 1 point = 1 bunch crossing by guinea-pig parametrization (polynomial) slope at nom. value  taylor coefficient i,j

Analysis Problems I at nominal value  simulate 10 bunch crossings  calculate spread assume same error for all points

((A+C) – (B+D)) / total energy Analysis Problems II bunch rotation in mrad total energy slope = 0 at nom. Parameter linear approximation fails true for all observables  analysis fails

1 st Results: Single Parameter Analysis nominal our precisionBeam Diag. Bunch width x Ave. Diff. 553 nm 1.2 nm 2.8 nm ~ 10 % Bunch width y Ave. Diff. 5.0 nm 0.1 nm Shintake Monitor Bunch length z Ave. Diff. 300 μm 4.3 μm 2.6 μm ~ 10 % Emittance in x Ave. Diff mm mrad 1.0 mm mrad 0.4 mm mrad ? Emittance in y Ave. Diff mm mrad0.001 mm mrad ? Beam offset in x Beam offset in y 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

1 st Results: Two Parameter Analysis Example: vertical waist shift Sngl Param Reso: 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

nominal setting (550 nm x 5 nm) σ x = 650 nmσ y = 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 ?