1 / 23

Performance of a Water Cherenkov Detector for n e Appearance

Performance of a Water Cherenkov Detector for n e Appearance. Shoei NAKAYAMA (ICRR, University of Tokyo) November 18-19, 2005 International Workshop on a Far Detector in Korea for the J-PARC Neutrino Beam @ KIAS, Seoul, Korea. Motivation. SK : OA 2.5 o

blake-noble
Download Presentation

Performance of a Water Cherenkov Detector for n e Appearance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Performance of a Water Cherenkov Detector for ne Appearance Shoei NAKAYAMA (ICRR, University of Tokyo) November 18-19, 2005 International Workshop on a Far Detector in Korea for the J-PARC Neutrino Beam @ KIAS, Seoul, Korea

  2. Motivation • SK : OA 2.5o • A far detector in Korea has the option to choose a site for a smaller off-axis angle. higher energy neutrino beam • Check the signal/BG separation performance for higher energy neutrinos • p0 BG is dominant for ne search. efficient p0 BG rejection g g g g

  3. Current T2K Selection Criteria for ne Appearance • Standard SK cuts : • fiducial volume, fully-contained, Evis > 100 MeV • single-ring • electron-like PID • no decay-e • 0.35 < Enrec < 0.85 GeVEnrec = (mNEe-me2/2)/(mN-Ee+Pecosqn-e) • Further p0 cuts : • cosqne < 0.9 • DL < 80, Mp0 < 100 MeV/c2 of p0 fitter (POLfit)

  4. POL(Pattern of Light)fit –p0 fitter – • Target: FCFV 1R-elike events • DL≡Likelihood(2g assump.) – Likelihood(electron assump.) • Try to reconstruct two g rings • Input: vertex, visible energy, and the 1stg direction by the standard fitter • Compare observed & expected (direct+scatter) charge • Vary the 2ndg direction and the energy fraction until the best match foundMp0 etc. POLfit g2 g1 standard fitter 500 MeV/c p0 true Pg2 = 55.5MeV/c rec.Mp0 =140.4MeV/c2

  5. S. Mine (UCI) @ NP04 Events vs. Selections Dm2 = 2.5x10-3 eV2 sin2 2q13 = 0.1 104 nm BG • Event selections: • FCFV, Evis > 100 • 2. 1 ring • 3. e-like • 4. no decay-e • 5. 0.35 < Enrec < 0.85 • 6. p0 cuts: • - cos < 0.90 • - DL < 80, Mp0 < 100 events/22.5kt/5yrs ne signal ne BG 10 event selections

  6. S. Mine (UCI) @ NP04 Events vs. Selections (cont’d) Dm2 = 2.5x10-3 eV2 sin2 2q13 = 0.1 (events / 22.5kt / 5yrs) ~20% ~70%

  7. This study uses … • the SK-I atmospheric n MC sample • to study the higher neutrino energy range than that of the OA2.5 beam MC • contains both ne and nm events • livetime: 100yrs • the maximum-likelihood analysis • to select neCC signals efficiently • pre-cut : FCFV, Evis>100MeV single-ring e-like no-decay-e

  8. Dist. for making a neCC-enriched likelihood (1) nmCC + NC neCCQE ring-counting parameter Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  9. Dist. for making a neCC-enriched likelihood (2) nmCC + NC neCCQE PID parameter Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  10. Dist. for making a neCC-enriched likelihood (3) nmCC + NC neCCQE cos qn-e Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  11. Dist. for making a neCC-enriched likelihood (4) nmCC + NC neCCQE p0 mass by POLfit Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  12. Dist. for making a neCC-enriched likelihood (5) nmCC + NC neCCQE DL by POLfit Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  13. Likelihood distribution FCFV, Evis>100MeV single-ring e-like no decay-e Likelihood neCCQE nmCC + NC  good separation

  14. Likelihood distributions for each energy range nmCC + NC neCCQE Likelihood Evis : 100 ~250 MeV 250 ~ 400 MeV 400 ~ 600 MeV 600 ~ 900 MeV 900 ~ 1500 MeV 1500 ~ MeV

  15. Events vs. Selections (100yr atm-n MC) rec En: 0~0.35 0.35~0.85 0.85~1.5 1.5~ nmCC FCFV,evis : 44073 44408 28071 39884 1ring : 32339 31059 18170 23668 e-like : 522 572 577 1187 no decay-e : 166 177 234 516 likelihood : 43 (25.9%) 70 (39.5%) 59 (25.2%) 116 (22.5%) NC FCFV,evis : 21872 11274 3851 5549 1ring : 4734 3379 1397 1967 e-like : 2622 2857 1342 1919 no decay-e : 2374 2611 1183 1379 likelihood : 290 (12.2%) 667 (25.5%) 325 (27.5%) 545 (39.5%) neCC FCFV,evis : 26678 36401 18921 25904 1ring : 20444 28583 13189 14432 e-like : 20294 28316 13091 14333 no decay-e : 19278 26667 12001 12437 likelihood : 17502 (90.8%) 22201 (83.3%) 9379 (78.2%) 7328 (58.9%)

  16. Likelihood distributions for each sample nmCC NC neCC rec En: 0~0.35 0.35~0.85 0.85~1.5 1.5~

  17. Efficiency by the likelihood cut nmCC rec En: 0~0.35 0.35~0.85 0.85~1.5 1.5~ NC neCC Likelihood>0.0 Efficiency Likelihood>0.5

  18. Composition of neCC interactions in the final sample neCC multi p neCC single p Fraction WC detector cannot reconstruct the neutrino energy of these events. neCC QE True neutrino energy (GeV)

  19. Summary • The signal/BG separation in a water Cherenkov detector for the ne appearance experiment has been developed based on a likelihood analysis. • The performance of the signal/BG separation was checked in the higher neutrino energy for a smaller off-axis site of a far detector in Korea. • In the higher energy region, the performance of the separation is worse. In addition, the fraction of CC non-QE interaction in the final sample is larger, whose parent neutrino energy cannot be reconstructed correctly.

  20. Supplement

  21. Events vs. Selections (100yr atm-n MC) true En: 0~0.35 0.35~0.85 0.85~1.5 1.5~ nmCC FCFV,evis : 343 44358 42139 69596 1ring : 325 41521 31935 31455 e-like : 7 527 709 1615 no decay-e : 4 192 243 654 likelihood : 1 (25.0%) 61 (31.8%) 79 (32.5%) 147 (22.5%) NC FCFV,evis : 261 4551 7177 30557 1ring : 52 1363 2426 7636 e-like : 51 1254 1814 5621 no decay-e : 51 1240 1717 4539 likelihood : 2 ( 3.9%) 204 (16.5%) 356 (20.7%) 1265 (27.9%) neCC FCFV,evis : 15212 32525 21705 38462 1ring : 14305 29203 15765 17375 e-like : 14210 28936 15637 17251 no decay-e : 14168 27630 13998 14587 likelihood : 13144 (92.8%) 23517 (85.1%) 10931 (78.1%) 8818 (60.5%)

  22. Likelihood distributions for each sample nmCC NC neCC true En: 0~0.35 0.35~0.85 0.85~1.5 1.5~

  23. Efficiency by the likelihood cut nmCC true En: 0~0.35 0.35~0.85 0.85~1.5 1.5~ NC neCC Likelihood>0.0 Efficiency Likelihood>0.5

More Related