Beam Monitoring from Beam Strahlung

1. Beam Monitoring from Beam Strahlung • work by summer students • Gunnar Klämke (U Jena, 01) • Marko Ternick (TU Cottbus, 02) • Magdalena Luz (HU Berlin, 03) • Regina Kwee (HU Berlin, 03) • New student, summer 04 Achim Stahl DESY Zeuthen 16.Apr.2004

2. Beam Strahlung Diagnostics of bunches at IP GeV/mm2 • 3 potential sources of information • energy-distribution of pairs • number-distribution of pairs • distribution of photons • Over-simplified detector simulation • detectors subdivided into cells • sum energy impact on cells • main source of uncertainty •  stat. fluctuations of beam-str. Linear approximation

3. Redesign for larger L*

4. D A C B Observables • total energy • first radial moment • first moment in 1/r • thrust value • angular spread • E(ring ≥ 4) / Etot • (A + D) – (B + C) • (A + B) – (C + D) • E / N forward / backward calorimeter

5. Taylor Matrix Observables Observables Δ BeamPar = + * nom 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. Solve by matrix inversion (Moore-Penrose Inverse)

6. parametrization (polynomial) 1 point = 1 bunch crossing by guinea-pig slope at nom. value  taylor coefficient i,j Slopes observable j beam parameter i

7. Example: Slopes

8. 1st Results: Single Parameter Analysis

9. What’s new: • consolidation of code • new observable: E(ring ≥ 4) / Etot • normalization of observables O/σ • use of external measurments • first look at real bunch trains

10. Single Parameter Analysis

11. Single Parameter Analysis Test of Linearity Range

12. Single Parameter Analysis weight of individual observables

13. Two Parameter Analysis Example: horizontal beam size Sngl Param Reso: 1.5 nm

14. Multi Parameter Analysis σx Δσx σy Δσy σz Δσz 0.3 % 0.4 % 3.4 % 9.5 % 1.4 % 0.8 % 1.5 % 0.9 % 0.3 % 0.4 % 3.5 % 11 % 0.9 % 1.0 % 11 % 24 % 5.7 % 24 % 1.6 % 1.9 % 1.8 % 1.1 % 16 % 27 % 3.2 % 2.1 %

15. Multi Parameter Analysis Test with non-nominal bunches: e- e+ nom. bunch size x: 575nm 575nm 553nm bunch size y: 5nm 7nm 5nm bunch size z: 290μm 320μm 300μm

16. Full Analysis

17. Real Beams: first look Example of 2 observables:

18. Real Beams: first look Single Parameter Analysis: σx

19. LumiCal 1st layer: measures N all layers: measure E 3 Sources of Information • energy-distribution of pairs • number-distribution of pairs • distribution of photons up to now: only energy distribution of pairs used test: number-distribution of pairs • new observable • Npairs / Etot

20. Number Distribution weight of new variable

21. Number Distribution Example: 6-Par. Analysis  roughly 10% improvement

22. First Look at Photons

23. σx = 650 nm σy = 3 nm First Look at Photons nominal setting (550 nm x 5 nm)

24. Conclusions: • Interesting resolutions achieved from single bunches • Multi-parameter analysis possible • Electron – Positron bunch can be separated • Not all parameters measurable Next Steps: • Include non-linear terms • understand realistic beam simulation • include photons ? impact on calorimeter design ?

25. 1st Fit with non-linear Terms

26. 1st Fit with non-linear Terms

27. The Mask • LumiCal shields detector against • back scattered beam strahlung • synchrotron radiation of final focus QUADs • neutrons from the dump

28. The Mask • LumiCal shields detector against • back scattered beam strahlung • synchrotron radiation of final focus QUADs • neutrons from the dump 5 cm graphits 10 cm graphits

29. VTX-Detector: Simulations by Karsten Büsser, Hamburg

30. Simulations by Karsten Büsser TPC: TDR slight increase in background ? optimization possible ?  more in Paris new: 20 mrad crossing new: 0 crossing