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Current Status of Luminosity Measurements with CMD-3 at VEPP-2000

This outline discusses luminosity measurements at the CMD-3 detector at VEPP-2000, including energy scans, preliminary results, and future plans. The importance of accurate luminosity determination for experiments at e+e- colliders is highlighted, particularly for improving the (g-2) of muons. Details of the VEPP-2000 layout and CMD-3 detector components are presented, along with event selection criteria and luminosity determination methods. The study aims to enhance the accuracy of (g-2) measurements by improving current techniques and exploring new decay modes and intermediate dynamics. The plot shows the hadronic contribution to the muon's anomalous magnetic moment at different energy levels, emphasizing the need for precise energy measurements for reliable results.

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Current Status of Luminosity Measurements with CMD-3 at VEPP-2000

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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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