BELLE/BABAR present background situation

1. BELLE/BABAR present background situation • The information from BELLE: http://www.phys.hawaii.edu/~superb04/slides.html • Most important talks: • Summary from Haba-san, • Current Belle background from Tajima-san • Also some informal inputs Guy Wormser, Super B-Factory Workshop, Jan 04

2. BELLE Background general features • Coasting backgrounds • Overall smaller background level • « SVT » background perfectly described by the sum of SR, beam gas and Touschek • Strong Touschek effect seen in the DCH • TOF (+50%) and Muon (x5) see larger bkg in collision than sum of single beams • Injection backgrounds: not a problem ! • Burst events: Happen one every few hours, last ~1 sec, spontaneously digested • Trips: a few per day Guy Wormser, Super B-Factory Workshop, Jan 04

3. SVD Upgrade in 2003 summer rbp = 1.5 cm 4 layers > 10 MRad (DSSD) > 20 MRad (readout chip) rbp = 2.0 cm 3 layers Rad. hardness ~ 1 MRad  Better vertex resolution / tracking efficiency Guy Wormser, Super B-Factory Workshop, Jan 04

4. Other sub-detectors No large difference for BG (current diff. causes small diff. ?) No problem Guy Wormser, Super B-Factory Workshop, Jan 04

5. 10% occupancy means 10k ch has unnecessary hits! Guy Wormser, Super B-Factory Workshop, Jan 04

6. Extraction SR in HER Single Beam HER Particle SR 50 mA 200 mA 100 mA Cool work! Hard-SR simulation 400 mA 600 mA 800 mA Guy Wormser, Super B-Factory Workshop, Jan 04 O. Tajima

7. translated differently as Unbelievable ! (Karim) I don’t believe it (Steve, O) Guy Wormser, Super B-Factory Workshop, Jan 04

8. Study of Touschek Effect Smaller beam-size (larger density)  larger background Touschek contribution < 20 % at collision ~ 50 % at single beam 31 % in simulation Touschek contribution must be corrected What we learn here is beam is different for collision. If no Touschek Collision run Single beam run Guy Wormser, Super B-Factory Workshop, Jan 04 O. Tajima

9. Towards a quantitative comparison • Some numbers available but direct detailed quantitative comparison with BABAR is not yet possible!! • BELLE figures of merit • Integrated dose in Calorimeter 100 Rad • Dose rate in SVT layer1, not very much phi dependant 100 krad • Integrated dose in all their SVTs 1M Rad • Current drawn from their chamber 1 mA • Seems certainly more confortable than here but by how much?How to compare: • BELLE_SVT first layer: Occupancy 10% but long shaping time (800ns)Dose: remove injection, radius different, different lengths,…DCH different volume, gas gainEMC remove injection, check theta dependencies,etc… Guy Wormser, Super B-Factory Workshop, Jan 04

10. Comparison templates (1) • System SVT Layer 1 • Sensor used: Occupancy • Strip width, lenght, radius, integrating time • Parametrization as fct of HER (2nd degree polynomial), LER (idem) for single beams • Plot of [observed – sum singles] vs lumi • Integrated dose as function of integrated lumi for running • integrated dose during injection • Ratio of max/min as function of Phi • Average Trip rate per day from the SVT protection system • Bias On/off during injection? Guy Wormser, Super B-Factory Workshop, Jan 04

11. Comparison template (2) • System DCH • Sensor : Total current draw • Gain, volume, min-max radius,length • Parametrisation as function of single beams (second order poly) • Plot of (observed –sum of single beams) as function of lumi • Integrated dose per wire in C/cm • Average spikes due to dust event per day; average trip per day • Signal any strong azimutal of z dependance Guy Wormser, Super B-Factory Workshop, Jan 04

12. Touschek effect at PEP-II Guy Wormser, Super B-Factory Workshop, Jan 04

13. Sensor BLLC2081 as fct of HER and LER Guy Wormser, Super B-Factory Workshop, Jan 04

14. Beam and beam and Touschek Guy Wormser, Super B-Factory Workshop, Jan 04

15. BLSC 3072 Guy Wormser, Super B-Factory Workshop, Jan 04

16. 3072 vs HER Guy Wormser, Super B-Factory Workshop, Jan 04

17. Comparison template (3) • System EMC • Sensor : Number of clusters above 1 MeV (or mean energy per cluster?) • Radius, crystal size, shaping time, amount of X0 in front • Single beam parametrization (second order polynomials) for Her and LER • Observed –(sum of singles) as function of Lumi • Integrated dose Maps as function of Tetha; as function of integrated lumi • Any azimutal effect? Guy Wormser, Super B-Factory Workshop, Jan 04

18. Extrapolations for SUPERKEK and Super PEP • THe IR design is key to the background level • The consensus IP looks like the present KEKB but with more magnetic field and closer to detector: the sensitivity to rad Bhabbas will increase compared to present KEK • SuperK rule of thumb: x20 all present background • Not so conservative in my mind because the present KEKB background is well described by just the sum of SR, BeamGas and Touschek but I have strong doubts this will be the complete list at 10**35 • On teh other hand, it makes no sense to extrapolate present PEP-II numbers x100 since the Super IR should be more background friendly than the present one. Guy Wormser, Super B-Factory Workshop, Jan 04

19. Conclusions • KEKB background situation is certainly better than ours. This is due to the absence of sweeping fields very close to the IP • A detailed comparison is not yet possible but is very desirable. I would like an agreement/comments on the proposed templates, and send them to KEK while we fill them • KEKB is able to describe their inner background by a sum of only three terms: SR, Beam Gas and Touschek • We need to make an effort to quantify our SR and Touschek contributions. • The neutron rate outside of the detector is another critical element (they have a very large collision term in the muon system, although the overall rate is low) Guy Wormser, Super B-Factory Workshop, Jan 04