CDF Luminosity Monitor for Run II

Transcription

1 CDF Luminosity Monitor for Run II presented by Sergey Klimenko CMS L Workshop, November 18-19, 1999

2 CDF II detector

3 People University of Florida (sole responsibility) D.Acosta,, J.Konigsberg, A.Korytov, G.Mitselmakher, A.Nomerotski, A.Safonov, D.Tsybychev. Design, construction, installation, operation, measurements, L for Tevatron & CDF II Fermilab & other institutes: M.Wong, R.Stanek, D.Northaker, R.Vidal, J.Elias, P.Lukens, R.Roser, A.Byon, P.Wison, F.Lewis, R.Kephart, C.Newman-Holmes, C.Nelson, T.Shaw, E.Hahn, B.Wands, H.Mendez, S.Lammel, C.Olson, H.Carter, D. Aspach, B.Cyko, P.Derwent, D.Allen, S.Segler, P.Murat, etc. Engineering, DAQ, Tevatron links

4 CLC chronology September 96 - March 97 Simulation studies CLC best April 97 - May 97 Prototype design and construction June 97 - September 97 Testbeam studies September 97 - March 98 Analysis & Documentation CLC works Conceptual Design CDF & Lehman reviews, CLC budget March 98 - December 98 Engineering design January 99 - October 99 Construction October 99 - June 00 CLC installation / DAQ commissioning July Luminosity measurements

5 Tevatron Luminosity in Run II L= cm -2 s pp per crossing integrated L to <5% provide online L Run I feedback to accelerator - bunch by bunch during normal run - operate during beam commissioning - operate during accelerator studies standalone, linear, stable, simple possible single interaction trigger possible trigger for diffractive physics Run I BBC counters won t work Run II Poor segmentation: 16/side/2.6 units of rapidity already saturated at 1.8 interactions/crossing 10 o hole reduced to 3 o hole rate was dominated by secondaries

6 Reference Process σ x = σ LM R x /R LM Inelastic PP scattering L - instantaneous luminosity L = f µ/σ f - frequency of bunch crossings m - average # of interactions/b.c s - inelastic cross-section large acceptance small angles used to measure by BBC in Run I satisfies all Run II L requirements W production need full understanding of tracking, particle-id, missing-e T, backgrounds, etc. loose real-time monitoring use as a cross-check for final L

7 Luminosity Measurement Measured value: µ ~ = ε(µ) µ -log(po); Po-probability of 0; Po=e -εµ ~ 0.2% N h ; counting hits; saturates N p ; counting particle; ~L N TC ; timing vertex counting with ToF; need excellent Time clusters σ=1.4ns >100ps Need to measure number of primary particles arrival time Detector: Gas Cherenkov Counters

8 Gas Cherenkov Counter 5cm 200cm gas radiator θ particle cone collector pmt Cherenkov radiation N pe = N o L <sin 2 θ > N o = 370 ε col (E) ε det (E) de cosθ = 1/( n β ) ε col - light collection efficiency ε det - PMT quantum efficiency 1atm n= , θ =3.1 o No = 200 (quartz window) Npe=110 (L=200cm)

9 Collection Efficiency Reflectivity Al greasing angles mylar Al+MgF2 Al Cone 80% greasing angles <4deg. 2 reflections in average Collector 90% large angles one reflection

10 PMT Window Quartz vs glass radiation hard UV collection (signal x2) 36% glass 100% quartz Small thickness to reduce radiation in the window ~25p.e./mm

11 Cherenkov Luminosity Counters (CLC) Particles/side /PP total IP Beam pipe primary plug 3 o hole 3 layers/side 16 counters/layer 96 counters total pointing to interaction point gamma threshold γ~20 excellent timing good amplitude resolution radiation hard select primary particles reject secondary particles can resolve particles

12 Cherenkov threshold γ th =20 All particles primary

13 CLC Amplitude Simulation, MBR events, 48counters/side 1 ppbar/bunch crossing secondary particles particles from interaction point plug primary particles count number of primary particles! 5 ppbar/bunch crossing 1 particle 2 particles

14 PMT window & electrons Fraction of particles that hit window all particles hit window Electrons contribution electrons

15 CLC parallax IP beam

16 CLC prototype Testbeam Fermilab Ad, Td Ac, Tc Au, Tu X,Y SCdown CLC prototype SCup beam drift chamber: measure coordinate transverse the beam main questions: - radiator light yield and collection efficiency - timing resolution

17 Isobutane Light Yield As a function of radius relative to the cone & PMT axis gas + PMT PMT gas 126 1atm.

18 Amplitude resolution isoc 4 H 10 (1.45atm) + XP2020 R<6mm (from cone axis)

19 PMT Window Light Yield quartz: 25p.e./mm 2mm 1mm PMT center

20 Time Resolution R5800Q: Ch amplitude p.e. σ T = 86ps

21 Time Resolution R2076: Ch amplitude p.e. σ T = 46ps

22 List of tasks accomplished in FY98 mechanical design CLC - CDF integration CLC location inside the plug interference with other subsystems assembly procedure mockups & measurements CLC mechanical design issues 2 layers vs 3 layers assembly scheme CLC alignment requirements cone modules assembly procedure parts specification & design outer shell stresses calculation cone & light collector optimization tolerances & clearances signal, HV, calibration & gas connectors final element analysis magnetic field shielding double stage shielding (pre-shield + shield) simulation shielding optimization test measurements CLC engineering drawings

23 Magnetic pre-shield Bz~125G Bz<15G Br~40G Br<6 G

24 µ-shield

25 CLC components 1. Outer shell (2atm) o 0.06 (1.5mm) Front window cone (1.mm) cylinder 0.4 (10mm) (2.mm) cover plate 2. Inner components collectors cones PMTs

26 CLC design

27 CLC readout Amplitude number of particles background rejection Time Z profile number of time clusters background rejection CDF trigger CDF data + CLC info bank for physics & calibration + integrated L bank for online Bunch Crossing Trigger + CLC amplitudes for all bunch crossings in one TEV turn for bunch by bunch luminosity unbiased trigger for CLC absolute calibration

28 CLC info

29 Summary Run II will be challenging in terms of beam conditions. Simulation shows Cherenkov is the best choice satisfies Run II Lum. specs From testbeam we learned large signal (~110p.e.) good light collection (AL mylar) many gases avail. (isoc4h10 is the best) excellent timing (50-90ps) Mechanical design - completed Construction - completed Ready for experiments - summer 2000