Detectors for VEPP-2000 B.Khazin Budker Institute of Nuclear Physics 2 March 2006

VEPP-2000 CMD-3 SND circumference – 24.4 m revolution time – 82 nsec beam current – 0.2 A beam length – 3.3 cm energy spread – 0.7 MeV  x =  z =6.3 cm L = cm -2 s -1 at 2E=2.0 GeV L = cm -2 s -1 2E=1.0 GeV Total integrated luminosity with all detectors on VEPP-2M ~ 70 pb -1

Detector requirements “Full” solid angle High energy and coordinate resolutions for photons Perfect reconstruction of events with many charged particles K/  /μ separation Antineutron (neutron) identification

1 – VEPP-2000 vacuum chamber, 2 – tracking system, 3 – aerogel counters, 4 – electromagnetic calorimeter NaI(Tl), 5 – vacuum phototriodes, 6 – absorber, 7-9 – muon system, 10 – VEPP-2000 phocusing solenoid Spherical Neutral Detector

Cryogenic Magnetic Detector-3 1 – vacuum chamber 2 – drift chamber 3 – electromagnetic calorimeter BGO 4 – Z – chamber 5 – CMD SC solenoid 6 – electromagnetic calorimeter LXe 7 – electromagnetic calorimeter CsI 8 – yoke 9 – VEPP-2000 solenoid

SND tracking system – - 24 jet cells, 9 drift layers with  ~ 0.2 mm - cathode strips on inner and outer shells with  ~ 0.3 mm - along wires charge division with  ~ 2 mm - MWPC on the outside of drift layers g/cm 2, 0.01 X 0, N,  ~  Tracking system

Carbon fibers with E  N/mm hexagonal cells ( 9 mm side) Sense wires - W-Re with 15 mcm diameter Field wires - gold plated Ti with 100 mcm diameter Gas mixture - Ar/isobutan (80/20) Cosmic event Drift resolution Resolution along wires

Calorimeter NaI(Tl) 1680 NaI(Tl) crystals in 3 spherical layers with vacuum phototriodes as photosensitive devices weight 3.5 tons, thickness 13.5 X 0  = 0.9× 4  1.NaI(Tl) crystals 2.Vacuum phototriodes Energy resolution:Angular reolution: Energy resolution

End cap calorimeter BGO 680 crystals 25×25×150 mm kg, 13.4 X 0  =0.3×4  HAMATSU silicon PIN 1×1 cm 2 Noise energy equivalent  noise = 1.2 MeV (t = 25  C)  noise = 1.0 MeV (t = 12  C) 22.7 MeV Cosmic particles Energy resolution for photons Angular resolution for photons

Calorimeter CsI 1152 crystals 60×60×150 mm X 0 8 octants by 9 rows of 16 crystals HAMAMATSU S B3 1×2 cm 2 Counter (1152) Row (72) Octant (8)

Calorimeter LXe 5.7 X 0 of LXe (400 liters, 1.2 tons) 14 gaps by 10.2 mm 2124 coordinate strips 264 towers anode cathode

Barrel system resolution CsI LXe LXe+CsI 500 MeV photons CMD-2 CMD-3

Calorimeter LXe  K separation Energy depositions in successive gaps for different momentum Pions Kaons 100 MeV/c200 MeV/c300 MeV/c 400 MeV/c500 MeV/c 600 MeV/c 700 MeV/c800 MeV/c900 MeV/c  K K  K  100 MeV/c200 MeV/c300 MeV/c 400 MeV/c 700 MeV/c 600 MeV/c 800 MeV/c 500 MeV/c 900 MeV/c  K  =1.5 %  K  =2.5 %  K  =3.5 %

μ 0 =10ph.e. π K μ 0 =5ph.e. 1,141,12 n Particle ID Aerogel Counters e/ ,  /K separation Aerogel + shifter + PMT Aerogel thickness 31 mm Shifter turned by 5˚ Teflon coverage (R=0.98) Nucl.Instrum.Meth.A315: ,1992 Counter efficiency Prototype with cosmic events

Particle ID: Timing Counter (SCiG) Energy deposition in 5 mm of scintillator m.i.p. Antineutron identification in e + e   n n bar Average number of photoelectrons per PMT ~ 10 Time resolution σ(TOF) ‹ 1 ns

Conclusions New generation of detectors perfectly matches the reach physics potential of VEPP-2000 Both detectors plan to the end of this year be ready to accept first luminosity