The CLOc Detector該cleoc探測(cè)器

1、the cleo-c detectorsteve graycornell universitybesiii workshopjanuary 13, 2004besiii workshopthe cleo-c detectorjanuary 13, 2004 2new era - new needs need quality tracking andprecision em calorimetery large 93% dw nearly hermetic full-range particle id simulate alternatives coordinate withstorage ri

2、ng expect high luminosity high statistics systematics dominate rare decays backgrounds matter fakes feed-down combinatoricsbesiii workshopthe cleo-c detectorjanuary 13, 2004 31.5 t now,. 1.0t later93% of 4psp/p = 0.35% 1gevde/dx: 5.7% p mini93% of 4pse/e = 2% 1gev = 4% 100mevtrigger: tracks & sh

3、owerspipelinedlatency = 2.5msdata acquisition:event size = 25kbthruput cleo-c83% of 4p87% kaon id with 0.2% p fake 0.9gev85% of 4pfor p1 gevbesiii workshopthe cleo-c detectorjanuary 13, 2004 4cleo iiiu(4s)typicalhadronicevent 10 tracks 10 showersbesiii workshopthe cleo-c detectorjanuary 13, 2004 5cs

4、ielectromagneticcalorimeter(end cap)csielectromagneticcalorimeterrichdrift chamberouter endplatedrift chamber endplatesmall radius sectioncos = 0.93ddmbesiii workshopthe cleo-c detectorjanuary 13, 2004 6drift chamber coordinated with ir 9796 sense wires 14 mm square cell 16 inner axial layers 31 ste

5、reo layers outer cathodesegmentation dz=1 cm; d=2p/8 thin inner tube 0.12% x0 60:40 helium-propanebesiii workshopthe cleo-c detectorjanuary 13, 2004 7besiii workshopthe cleo-c detectorjanuary 13, 2004 8drift chamber performance avg. residual 85 mm best 65 mm mc agreement momentum resolution dp/p=0.7

6、% at 5 gev/c dp/p=0.3% at 1 gev/c ms limited lower momentum spectrum multiple scattering limited dp/p no vertexing needed replace silicon with low-mass z tracker similar mass resolution more layers - better track recognitionbesiii workshopthe cleo-c detectorjanuary 13, 2004 10zd inner drift chamber

7、6 stereo layers: r=5.3 cm 10.5 cm 12-15o stereo angle |cos | 0.93 300, 10 mm cells 1% x0, .8mm al inner tube 60:40 helium-propane 20 mm au-w sense wires 110 mm au-al field wires outer al-mylar skinbesiii workshopthe cleo-c detectorjanuary 13, 2004 11zd drawingbesiii workshopthe cleo-c detectorjanuar

8、y 13, 2004 12besiii workshopthe cleo-c detectorjanuary 13, 2004 13tracking with zdp (gev/c)0.250.490.971.361.912.68z0 (m)806702684680672667sp/p (%)0.320.320.350.390.450.56zd calibration underway residuals now kp without & with rich cuts.80% eff, 8:1 bkg suppressionk-p separation (chisq differenc

9、e)besiii workshopthe cleo-c detectorjanuary 13, 2004 20rich performance designed for b decay excellent for d decay k p separation measured in data d*d0p+; d0 k-p+ high efficiency low p fake rates combine with de/dxcleo-cb physicskaon eff = 0.8kaon eff = 0.85kaon eff = 0.9besiii workshopthe cleo-c de

10、tectorjanuary 13, 2004 21csi calorimeter projective barrel endcaps 4 photodiode readout triple range adcs excellent photon finding electron id p0 & reconstructioncsielectromagneticcalorimeter(end cap)csielectromagneticcalorimeterrichdrift chamberouter endplatedrift chamber endplatesmall radius s

11、ectioncos = 0.93ddmbesiii workshopthe cleo-c detectorjanuary 13, 2004 22cleo csi at a glance 7800 csi(tl) crystals 5530 cm3 (16x0) 4 photodiode readout w/local preamps 229 crystals have 1 turned off (too noisy) 10 crystals have 2 turned off (6 in endcap) 0 have 3 or 4 turned off. 7 “dead” crystals i

12、n cleo iii (all in endcaps, 5 near inner or outer radii) external summation/pulse shaping & tdc total noise per crystal is 0.5 mev incoherent & 0.2 mev coherent light output losses calibrate awaybesiii workshopthe cleo-c detectorjanuary 13, 2004 23cleo ii - cleo iiibarrel unchangedbarrel unc

13、hanged tf removed, rich insertedtf removed, rich inserted dr lengthened & narroweddr lengthened & narrowed endplate material thinnedendplate material thinned endcap repackaged endcap repackaged pushed back 7 cmpushed back 7 cmbesiii workshopthe cleo-c detectorjanuary 13, 2004 24csi for cleo

14、iii & cleo-c barrel unchanged from cleo ii but dr/particle id changes increase minimally obstructed barrel from 70% to 80% of 4p “good barrel” is 14% bigger than cleo iis endcaps repackaged for new i.r. superconducting quadrupoles thinner dr endplate & better support design make less materia

15、l in front than cleo ii only 40%x0 , about 30% of cleo ii material “good endcap” coverage |cos| = 0.85 to 0.93 quality solid angle 25% than cleo ii new digitizing electronicsbesiii workshopthe cleo-c detectorjanuary 13, 2004 25csi performancebesiii workshopthe cleo-c detectorjanuary 13, 2004 26lesso

16、ns from the calorimeter endcaps reconfigured for cleo iii many crystals had lost signal with age glue joint had opened up endcap crystals reglued unable to fix barrel glue joints material matters much improved endcap performancebesiii workshopthe cleo-c detectorjanuary 13, 2004 27y yx, y m+m-cleo-c

17、muon systembesiii workshopthe cleo-c detectorjanuary 13, 2004 28trigger programmable (fpga), pipelined track and csi cluster primitives: tracks (pt150 mev/c) low, med, high shower clusters combine to define triggers, e.g.2 tracks + low shower99% for hadronic events for cleo-c reduce med & high t

18、hresholds add new neutral-only triggers implemented tile sharingbesiii workshopthe cleo-c detectorjanuary 13, 2004 29data acquisition vme & fastbus front ends designed for 1 khz & 4 mb/sec achieved 500 hz & 6 mb/sec several upgrades completed a few remain for spring 2004besiii workshopth

19、e cleo-c detectorjanuary 13, 2004 30summary new era of high luminosity makes new demands on the detector. the cleo-c detector is state of the art, understood at a precision level, now taking data in the charm region.besiii workshopthe cleo-c detectorjanuary 13, 2004 31credits calorimetry - brian heltsley daq - tim wilkson tracking - karl ecklund, dan peterson trigger - topher caulfieldbesiii workshopthe cleo-c detectorjanuary 13, 2004 32y yp+p-;