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INFN, FRASCATY 16-17 April, 2012

Current status of luminosity measurements with the CMD-3 detector at VEPP-2000 G.V.Fedotovich BINP, Novosibirsk. INFN, FRASCATY 16-17 April, 2012. Short outline. 1. VEPP-2000 and CMD-3 detector

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INFN, FRASCATY 16-17 April, 2012

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  1. Current status of luminosity measurements with the CMD-3 detector at VEPP-2000 G.V.Fedotovich BINP, Novosibirsk INFN, FRASCATY 16-17 April, 2012

  2. Short outline 1. VEPP-2000 and CMD-3 detector 2. Energy scan in runs 2011-20123. Luminosity determination4. Some preliminary results5. Nearest plans

  3. Motivation As a rule all hadronic cross sections in experiments at e+e- colliders are normalized on integrated luminosity For luminosity determination it is necessary to use well known QED processes which have the large magnitude of cross section and a simple signature in detector e+e-  e+e-, , +- (cross check capability) Why luminosity determination better than 0.5% is required Hadron contribution to (g-2) of muon is about 60 ppm 600.005 = 0.3 ppm Aim new FNAL experiment for (g-2) of muon is to improve BNL result by a factor of 4! Current accuracy 0.6 ppm

  4. CMD-3 Lay-out of VEPP-2000with round beams • revolution time – 82 ns beam current – 200 mA • beam length – 3.3 cm energy spread – 0.7 MeV • circumference – 24.4 m beta function in IP x=z =4.3cm • L = 1032cm-2s-1at 2.0 GeV Lpeak = 21031cm-2s-1 at 1 GeV SND

  5. Round beams Project L Received L

  6. 3D view CMD-3 detector DC – 1218 hexagonal cells with sensitive wires, W-Re alloy, 15 m in diameter. Z-chamber – start FLT, precise determine z-coordinate ~ 500  (detector acceptance) LXe calorimeter thickness 7 X0, 196 towers & 1286 strips. Spatial resolution 1 – 2 mm Calorimeter with CsI crystals (3,5 t), 8 octants, number of crystals - 1152, 8 X0. TOF – 16 counters, time resolution ~ 1ns MR system – 8 octants (cosmic veto, ~ 1ns) Project magnetic field - 1,5 T (current value 1.3 T while)

  7. CMD-3 detector

  8. First run: winter-spring 2011 event e+e-  e+e- R-z plane R- plane

  9. CMD-3 on-line monitor

  10. History of data taking in 2011 in 2012

  11. First step – collinear events selection 1. Hit points on track in DC >5 (max 19) 2. Total charge =0 3.Accolinearity angle in R -  plane: | | φ1-φ0|-π | < 0.15 rad 4. Accolinearity angle in R – z plane: |θ1 + θ0 -π| < 0.25 rad Event is Bhabha, if: • Number of cluster in LXe calorimeter is 2 exactly • Angle (π - 1.0) < ( θ1lxe- θ0lxe +π )/2 < 1.0 rad • Energy of every cluster E1,2 > Ebeam/2 • Number of hitted sectors > 1 Second step – Bhabha events selection

  12. Bhabha events • 1. Number of hitted wires (track belong) in DC >= 10 • 2. 500 MeV/c < P1,P2< 1500 MeV/c • 3. π-1.0 > ( θ1 +(π-θ2))/2 > 1.0 rad • Bhabha events areinside red box

  13. Luminosity determination L = Ne+e-/(σBornradε²DCε2cltr) Ne+e- -- number of the detected Bhabha events σBorn -- Born cross section rad -- radiation correction ( 0.95) εDC -- track reconstr. effic. in DC (99.2 ± 0.08)% εcl -- cluster reconstr. effic. in calorimeters tr -- charge trigger efficiency

  14. Track reconstruction efficiency in DC Events are selected using calorimeters information only: Look for two good quality clusters nLXe & nCsI = 2, E1 + E2 > 1.3Ebeam, E1,E2 < 1500MeV

  15. Clusters reconstruction efficiency Events are selected using DC and ZC information only: Selection conditions and cuts Two back-to-back tracks in DC and look for clusters in LXe calorimeter which belong to tracks Cuts φDC-φLXe <0.3 rad θDC-θLXe <0.4 rad As a result was found that: εcl = 0.995 (1000 MeV)

  16. Gamma-gamma events Selection condition & cuts No tracks in DC & ZC signals Energy every cluster > Ebeam/2

  17. Bhabha events 2E = 1.4 GeV Polar angle difference determined with LXe strips & towers: str(cp)- tower(cl)

  18. Gamma-gamma events Polar angle difference determined with strips & towers str(cp)- tow(cl)

  19. Ratio of luminosities Red points – scan up Blue points – scan down Number of points – 39, integrated luminosity ~ 20pb-1

  20. 2012energy scan 0.68  0.43

  21. Hadronic contribution to anomalous magnetic moment of muon This plot demonstrates how quickly integral reach the asymptotic value ~ 60 ppm. For s>2 GeV the contribution is about ~ 7 ppm only

  22. One of the main physical task is to measure quantity R(s) aμ(theory) = aμ(QED) + aμ(Weak) + aμ(Hadronic) Contribution to am vs energy 10 MeV step Contribution to error of am vs energy, 10 MeV step black points- statistic red points-systematic

  23. Derivative d|F(E)|²/dE/|F(E)|²x E/E (accuracy of energy determination) (E/E = 10-3) Derivative jumps up and down inside corridor 1%, but near  and  mesons reaches the values 6%. Very important taskto determine beam energy with relative accuracy E/E  10-4 or even better

  24. Exclusive decay modes Search for (1420) & (1650) decay into 3 vs energy a1(1260) is enough to describe cross section dependence vs energy for 4 channel. But at high statistic  channelwill contribute at noticeable level too? Search for intermediate dynamics is very importance. 5 channel with intermediate states (1420) & (1650) which decay to  5 channel with intermediate states (1450) & (1700) which can decay to  6 channel - gold mode for search (1900). What is the mass? It is upper or lower of the threshold production NNbar? Is this state baryonium?Hybrid or something else Search for decay(1680)K+K-, KSKL and strange vector hybrid in decays (1680)  K*K  KK  &  K1(1400)KK*K  KK. f0(980), , , radiation decays and physics of  и  mesons…

  25. Nearest plans? Collect the integrated luminosity in forthcoming season about 100 pb-1 Search for NÑ events, select and study detection efficiency for this process Study in detail 4, 5 and 6 channels & so on… (prepare preliminary results for coming conferences) New techniques is installed for beam energy determination using Compton’s back scattering (10-4). It had taken additional time before run (about 3 months). But this techniques does not operate while We loose about 30% of integrated luminosity due to problems with booster. Currently max. beam energy injection is limited by 850 MeV while. The rise time and fall time of beam energy in VEPP-2000 is a complicated procedure Luminosity is limited by positron storage rate (1031). New injection complex will provide project luminosity 1032 (only in couple years)

  26. Thanks for attention on behalf of the CMD-3 collaboration

  27. Second part Some preliminary results of the SND & CMD-3 based on data of 2011 G.V.Fedotovich BINP, Novosibirsk

  28. INFN, FRASCATY 16-17 April, 2012

  29. CMD-3 Lay-out of VEPP-2000with round beams • revolution time – 82 ns beam current – 200 mA • beam length – 3.3 cm energy spread – 0.7 MeV • circumference – 24.4 m beta function in IP x=z =4.3cm • L = 1032cm-2s-1at 2.0 GeV Lpeak = 21031cm-2s-1 at 1 GeV SND

  30. Round beams Project L Received L

  31. CMD-3 detector DC – 1218 hexagonal cells with sensitive wires, W-Re alloy, 15 m in diameter. Z-chamber – start FLT, precise determine z-coordinate ~ 500  (detector acceptance) LXe calorimeter thickness 7 X0, 196 towers & 1286 strips. Spat.ial resolution 1-2 mm Calorimeter with CsI crystals (3,5 t), 8 octants, number of crystals - 1152, 8 X0. TOF – 16 counters, time resolution ~ 1ns MR system – cosmic veto, ~ 1ns Project magnetic field - 1,5 T (current value 1.3 T while)

  32. CMD-3 detector

  33. SND detector 1 - vacuum chamber, 2 - drift chamber, 3 - cherenkov counters (airogel), 4 – calorim.NaI(Tl), 5 – phototriodes, 6 – iron absorbsion, 7-9 – muon range system Features «new» SND: 1. ID system (n=1.05, 1.13) 2. e/π separation E < 450 MeV 3. π/K separation up E < 1 GeV 4. new DC – more accurate solid angle determination

  34. SND detector

  35. SND detector

  36. PRELIMINARY SND RESULTS2011 DATA

  37. Mπ0γ e+e-→ ωπ0 → π0π0γ π0 Mp ω(782)

  38. e+e-→ ωπ0 → π0π0γ

  39. e+e-→ π+π-π0π0

  40. e+e-→ π+π-η () Selections: 2 charged particles 2 photons kinematic fit (π+π–γ γ): χ2< 20

  41. e+e-→ π+π-η

  42. e+e−→pp(SND, 2011) E<1905 MeV E>1910 MeV Proton not seen. STAR on the vacuum chamber wall – pbar annihilation Two tracks in DC with high dE/dx. Antineutron STAR outside of DC(ACC)

  43. e+e−→ppbar(SND, 2011) SND preliminary SND BaBar

  44. e+e−→nnbar(SND, 2011) star in calorimeter no signal in detector Big cosmic bgn

  45. e+e−→n-nbar(SND, 2011) Signal+ bgn bgn(pp + ggg) threshold

  46. PRELIMINARY CMD-3 RESULTS 2011 DATA

  47. Collinear events e+e-→ X+X-(Ec.m. = 1.95 GeV)) e+e- - used for luminositymeas. Currently ~1% syst. goal ~ 0.2- 0.3% e+e- cosmic m+m- p+p- P-P+ K+K- We plan to measure the e+e- -> P-P+, K+K-, p+p- processes in all en. range

  48. P-Pbar event in CMD-3

  49. Preliminary results for the e+e- -> P-Pbar study Number of events from momentum distributions Clear signature of the PbarP events Ec.m.=1.95 GeV Ec.m.=1.925 GeV Ec.m.=1.975 GeV Ec.m.=2.0 GeV

  50. Preliminary results: P-Pbar cross section

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