Electromagnetic calorimeters of the CMD-3 detector

Transcription

1 Electromagnetic calorimeters of the CMD-3 detector Budker Institute of Nuclear Physics D. Epifanov Outline: VEPP-2000 and CMD-3 Barrel calorimeter ( LXe + CsI) Endcap calorimeter ( BGO ) First results

2 ILU 3 MeV Linac VEPP-2000 Budker Institute of Nuclear Physics, Novosibirsk, Russia CMD-3 B-3M 200 MeV synchrobetatron BEP + e,e booster 900 MeV 2 m SND ee + convertor 2E = GeV, L = cm -2 s -1 Measurement of the e+ e- hadrons cross section in the energy range up to 2 GeV (improved determination of R(s)) Measurement of parameters of vector mesons ρ, ω, φ, ρ, ρ, ω, ω Check of the CVC (comparison with hadronic spectral functions from τ decays )

3 CMD-3 detector 1 Vacuum pipe, 2 Drift chamber, 3 BGO endcap calorimeter, 4 Z chamber, 5 Superconducting solenoid, 6 LXe barrel calorimeter, 7 CsI barrel calorimeter, 8 Yoke The main tasks for the calorimeters: Precise measurement of γ energy and coordinates in the wide energy range E = γ 10 MeV 1 GeV Hadron/electron separation Generate signals for the neutral trigger of the detector

4 LXe calorimeter Barrel (LXe+CsI) calorimeter Precise measurement of the coordinate of γ conversion point σ E /E = % (E γ = MeV) σ θ,ϕ = θ,ϕ LXe: ρ = 3 g/cm 3, w = 16 ev/pair Thickness 5X 0, Volume = 400 litre Purity (mean free path) 20 mm Temperature=170 K, Pressure=1.2 atm. L. nitrogen consumption 6 litre/hour 15 cylindrical electrodes ( 7 cathods, 8 - anods) with 10.2 gaps between them. R internal = 369 mm, R external = mm 8 Anods provide energy measurement in the 264 towers. 8 - along Z, and 33 - in the R-ϕ plane. 7 Cathods are divided into 2124 strips to measure coordinates (~300 strips per electrode )

5 LXe calorimeter Cathods (coordinate strips): typical amplitude el., noise ~ 2200 el Anods (energy towers): sensitivity el/mev, noise ~ 3000 el (0.22 MeV)

6 S ensitive D evice C M D -2 N channels D eadtim e 300µs R eado ut R ate 100H z LXe calorimeter A m p. + S haper M odules N Analog lines Event D i g i t i z i n g 200us N A nalog lines D igitizer M odules A U K LU K V A A D C B u s D e-r andom izer R e a d O u t 90us t S ensitive D evice C M D -3 N channels D eadtim e 60µs R eado ut R ate 1kH z N Analog lines Event D igitizing R eado ut 58us D e-r andom izer A m p. + Shaper + D igitizer M odules t A U AD C N /16 D igital lines D ata Tx/R x 200 serial links 16 concentrators Ethernet-100 strips towers Cathode (coordinate strips) Anode Charged particle's track

7 LXe calorimeter Calibration with help of the cosmic particles Reconstruction: hit, cluster, track Calculation of the spatial resolution Charged track q 2 q 1 q3 cluster induced charges q 1, q 2, q 3. Amplitude

8 CsI calorimeter Calorimeter consists of 8 octants Each octant is constructed from 9 modules Each module contains 16 counters (channels) Counter is made from CsI(Tl) or CsI(Na) crystal of 6 x 6 x 15 cm 3 size, 8X counters (total mass of the crystals is 2.8 tons ) CsI(Na) 6x6x15cm 3 Preamplifier teflon aluminized mylar PIN PD

9 CsI calorimeter Signals from all counters are processed by 39 32ch- Amplifier-Shaper-Digitizer boards From the boards the data come to the online PC-farm through the special interface board Finally information is recorded to the raw-data file

10 CsI calorimeter N counters /(20 KeV) hntlk Entries 1152 Mean RMS b) - CsI(Tl) and CsI(Na) - only CsI(Na) Noise (KeV) N counters /(200 ph.e./mev) CsI(Na) CsI(Tl) 10 hna htl Entries Mean RMS Light output (ph.e./mev) hist6 hist6 Entries Mean 1082 RMS χ 2 / ndf / 25 p ± p ± 19.8 p ± p ± 5.6 p ± p ± 18.1 p ± b)

11 CsI calorimeter Amplifier Shaper ADC Discriminator Summator ClusterFinder NT+ short-shaped signals from SPM Low-pass filter Time-tag signal ADC Signal processing channel Fast link bus Total energy deposition Energy deposition adder History memory "Fast" link to ClusterFinder Control bus Z CAMAC Interface 5 Y a) center of VEPP 2000 X "Slow" link Y X to Data System CsI LXe BGO BGO b) Z LXe: 80 trigger cells CsI: 80 trigger cells BGO: 48 trigger cells

12 BGO calorimeter Calorimeter contains 680 counters (total mass of the crystals is 450 kg) and covers 0.3*4π sterad. Counter is made from BGO crystal of 25 x 25 x 150 mm 3 size, 13.5X 0 σ E /E = 8 4 % (E γ = MeV) σ θ = rad Sensitivity 500 el./mev, σ el ~500 el. (1 MeV)

13 BGO calorimeter Light output increase ~ 20 % Electronic noise decrease ~ 10 % Special cooling system is used Operation of the calorimeter at T = 18 o C

14 BGO calorimeter Calibration with help of the cosmic muons Reconstruction of the clusters Calibration using Bhabha events Spectrum from the cosmic muons 5 10 BGO channels occupancy hh Entries 680 Mean RMS MeV 10 4 N events /chan BGO Channel

15 CMD-3 experimental event E γ = 350 MeV: LXe 80%, CsI 20% (MC) E γ = 950 MeV: LXe 70%, CsI 30% (MC)

16 Conclusion Calorimeters are installed in the detector Their electronics is integrated in the DAQ system Experimental runs have been started Monitoring of all channels is doing with calibration signal from the generator Energy calibration is doing with help of the cosmic muons Work on the procedure of energy calibration with Bhabha events is in progress Neutral trigger system is tested and will be included soon Works on the global reconstruction of the event are in progress

17 Backup slides

18

19 Source of error 2pi s<1 GeV 2pi s>1.0 GeV 4pi s>1.1 GeV Event separation 0.2% 0.2% 1% (cuts) Fiducial volume 0.2% 0.2% 2% (model) Energy calibration 0.1% (0.3%) 0.1% (1.0%) 1% Efficiency correction 0.2% (0) 0.2% (0) 1% (tr+bg) Pion losses (decay, NI) 0.2% (0.1%) 0.2% (0.1%) Other 0.3% (.) Radiative corrections 0.15% 0.15% 1% Total 0.4% 0.4% 2.5% Total (no dep.) 0.5% 1.0% Total (high eff.) 0.3% 0.3%

20 DAQ VEPP2000 Storage Ring SND RF Cavity Freq. Bunch Crossing Particle Injection MChS - Command, Clock to Event Builder Switch CMD-3 Clbr Pulser Clbr Pulser Clbr Pulser Tracker Frontend Calorimeter Frontend TOF&Mu Frontend Track Finder Claster Finder Extended Decision Digitizer T2Q Digitizer SAD Digitizer TQ Data Delivery Groupe 1 Data Delivery Groupe

21

22

23