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Status of Super-Kamiokande, K2K and JHF n

Status of Super-Kamiokande, K2K and JHF n. Yuichi Oyama (KEK). for Super-Kamiokande collaboration,. K2K collaboration and JHF n collaboration. Dec-15-2003. ACFA LC WS @Mumbai. Super-Kamiokande. 50kt water Cherenkov detector with 11146 20-inch F PMTs. ●.

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Status of Super-Kamiokande, K2K and JHF n

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  1. Status of Super-Kamiokande, K2K and JHFn Yuichi Oyama (KEK) for Super-Kamiokande collaboration, K2K collaboration and JHFn collaboration Dec-15-2003 ACFALC WS @Mumbai

  2. Super-Kamiokande 50kt water Cherenkov detector with 11146 20-inch F PMTs. ● Located at 1000m underground in Kamioka mine, Japan ● Operation since April 1996. ● Discovery of neutrino mass using atmospheric neutrinos. ● Precise study of solar neutrino oscillations. ●

  3. Super-Kamiokande accident on November 12, 2001 The implosion of one PMT created shock waves which triggered a chain reaction to destroy the other PMTs. ● 6661 inner PMTs and 1017 outer PMTs were broken. ● Remaining ~5200 PMTs are covered by Acrylic + FRPvessels. The experiment was restarted with about half PMT density in December 2002. ●

  4. Jan.-2003, fully contained event Present status of Super-Kamiokande The experiment is successfully in operation ! ● Super-Kamiokande -II Calibration and modification of analysis tools for SK-II are in progress. ● Enjoying interesting topics of SK-I data: ● g-ray burst, relic supernova neutrino, ne from the Sun, 3 flavor oscillation, WIMP search, solar neutrino modulation, p0/m ratio, upward-going muon astronomy, ntsearch, correlation with solar flare, neutrino magnetic moment, exotic mode of nucleon decay… A paper rush is coming!

  5. Overview of the K2K experiment First long-baseline neutrino oscillation experiment ● Muon neutrino beam generated at KEK is shot toward the Super-Kamiokande detector, which is 250km away from KEK ● Search for neutrino oscillations in the parameter region Dm2 >2×10-3 eV2 is possible. It covers the parameter regions suggested by the atmospheric neutrino anomaly. ●

  6. K2K neutrino beamline in KEK TRISTAN RING (B-factory) 12GeV PS Primary Beam-line P 12GeV/c proton beam 1.1msec beam duration Al Target 2.2sec accelerator cycle Intensity 6~7x1012 ppp Total 1020 p.o.t. Decay pipe (200m) p+ -> m+ + nm Muon Pit Front Detectors nm To Kamioka

  7. profile at SK spectrum at SK n/cm2 (x106) n/cm2 /0.1GeV(x106) 5 1 SK(0.2mrad) 3mrad 0 0 1 2 3 5 1 3 0 4 0 2 Neutrino energy (GeV) distance (km) Property of the neutrino beam The mean energy is about 1.3GeV and the peak energy is about 1.0GeV. ● Almost pure muon neutrino beam. ne/nm ratio is about 1%. ● The direction of the beam is adjusted within 1mrad. ● Nearly the same energy spectrum and flux within 3 mrad. ● (The size of SK is ~50m/250km = 0.2mrad) Neutrino flux at SK (250km downstream) is 1.3x106n/cm2 for 1020p.o.t. and ~170 events are expected in the 22.5kton of fiducial volume in the case of null oscillation. ●

  8. K2K Front Detectors at 300m from the target Trigger counters (a)1kt water Cherenkov detector (1kt) An 1/50 miniature of SK detector. Direct comparison with SK data (b)Fine-Grained Detector (FGD) Consists of 4 detector elements. Precise measurement of neutrino beam property.

  9. 100cm Study of the Neutrino beam in the Front Detectors Data recorded in the Front Detectors are used to study properties of the neutrino beam. ● Fine-Grained detector 1kt detector The beam direction, stability of the beam intensity, energy spectrum, ne/nmratio well agree with expectations. ● The excellent agreements between data and expectations in KEK site ensure the reliability of the expected beam at SK site. ●

  10. Summary of data-taking in K2K-I M.H.Ahn et al., PRL 90, 041801(2003) First neutrino beam: January 27, 1999 ● Physics run: June 4, 1999 – July 12, 2001 ● First neutrino event: June 19 1999 ● Total successful physics run: 234.8 days ● Total spill numbers: 9.22x106 spill ● Total POT for analysis: 47.8x1018 p.o.t. ●

  11. Neutrino events in Super-Kamiokande GPS KEK Kamioka Selection Evis > 30 MeV and no signal in the outer detector ● History of event accumulation time correlation with the neutrino beam Number of events 1.5ms Events within 1.5msec time window are selected because neutrino beam width is 1.1msec and accuracy of the absolute time determination by GPS is 0.2msec. ● Results P.O.T. (x1018) Number of events in the fiducial volume is 56. ● Expected atmospheric neutrino background is 1.3x10-3events. The rate of the neutrino events is uniform. ●

  12. data no oscillation Dm=2.8x10-3eV2 Number of events En(GeV) nm-ntoscillation analysis for K2K-I data +6.2 (1)We observed 56 neutrino events where the expectation is 80.1 -5.4 Number of neutrino events is considerably smaller than the expectation. (2)Neutrino energy distribution is calculated from 29 single ring m-like events. The result shows a slight discrepancy in 0.5-1.0GeV range. If null oscillation is assumed, such poor agreements happen with a probability ofless than 1%.

  13. K2K SK Constraints on nm-ntoscillation Dm2 ranges (1.5~3.9)x10-3eV2for sin22q=1.0@90%C.L. ● The best fit parameters are (Dm2,sin22q)=(2.8x10-3eV2, 1.0). ● The expectation of the total SK events is ~54, where data is 56. Agreement with the SK atmospheric neutrino results is excellent. ●

  14. Status of K2K-II K2K-II data taking is started in January 2003 and successfully in progress. ● The event rate is consistent with K2K-I. ● Number of events Further data-taking is scheduled in ● Oct.2003 – Feb.2004 and Oct.2004 – Mar.2005. POT (x1018)

  15. Tokai 295km Kamioka KEK JHFn experiment J-PARC in JAERI Next generation long-baseline neutrino-oscillation experiment ● High intensity neutrino beam from JHF 50GeV Proton Synchrotron in J-PARC is shot toward the Super-Kamiokande detector 295km away. ● Nominal beam intensity is about 100times larger than K2K. ● Letter of Intent : hep-ex/0106019

  16. J-PARC in JAERI, Tokai 400MeV Linac 3GeV PS Decay Volume To SK Pacific Ocean Target 50GeV PS What is J-PARC, JAERI, Tokai, JHFn J-PARC: Japan Proton Accelerator Research Complex. The name of the entire project. It includes High Energy Physics, Nuclear Physics, Life Science, Material Science, Nuclear Technology. Accelerators consist of 400MeV Linac, 3GeV PS and 50GeV PS. JAERI: Japan Atomic Energy Research Institute. The host institute of J-PARC Tokai: the name of the village where JAERI is located. JHF: Japan Hadron Facility. 50GeV Proton Synchrotron JHFn = J-PARCn =T2K : Name of the neutrino experiment. Official name is not fixed. J-PARC is under construction since 2001. ● JHFn has not been approved yet. If it will be approved in end of this December, the construction will start in April 2004, and the experiment will start in 2009. ●

  17. p p n off-axis on-axis 0m 140m 280m 2 km 295 km JHFn Beamline and Detectors Comparison of the proton beam Beamline Off Axis beam ● The center of the beam direction is adjusted to be 2o ~ 3o off from the SK direction. Detectors Muon monitors @ ~140m downstream ● First near detectors@ ~280m downstream (boundary of the JAERI site) ● Second near detectors@ ~2km downstream ● Far detector@ 295km downstream (Super-Kamiokande) ● “Off axis beam” and “2km detector”

  18. n1 ( ) n2 > > n3 ~ ~ ne ( ) nm nt Neutrino mass matrix and physics goal of JHFn If neutrinos have mass, the flavor eigenstates are mixtures of the mass eigenstates. The neutrino mass matrix, U, has 6 parameters. ● 2 square mass differences (Dm122, Dm232), = U 3 mixing angles (q12,q23,q13) 1 CP violation phase, d. Dm122and q12 were determined by solar/reactor neutrino oscillation. ● Dm122~ (6~8)x10-5eV2, sin22q12 ~ 0.8 Dm232and q23 were determined by atmospheric/K2K neutrino oscillation. ● Dm232~ (2~3)x10-3eV2, sin22q23 0.9 Remaining unknown parameters are q13 and d. ● Complete understanding of neutrino mass matrix (1)First observation of finite q13 if sin22q13 0.006. (2)Precise measurements of Dm232 and q23 D(Dm232)~0.1x10-3eV2, D(sin22q23)~0.025 (3)Observation of d by JHFn upgrade (4MW) + Hyper-Kamiokande

  19. e+ + ne + nm Measurement of q13 by ne appearance q13 can be determined by observing ne appearance. ● P(nm ne) y sin2q23sin22q13sin2(1.27Dm232L/En) Dm232 ~ (2~3)x10-3eV2 sin2q23~0.5 (the same Dm2 as atm. n oscillation) q13 is expected to be small because it is the mixing angle between 1st and 3rd generation. Present upper limit is sin22q13 ~ 0.1. Small ne appearance signal must be searched for. To increase ne appearance signal The oscillation probability should be maximized. Neutrino beam energy is adjusted according to Dm232 . ● To reduce background ne background is generated with muon decay in the decay pipe. ● p+m+ + nm ne background To reduce the ne fraction in the nm beam, a short decay pipe is used. It is 110m and ne/nm ratio is 0.2%. (In K2K, 200m and 1.3%) Excellent e/m identification in SK. Identification of neutral current p0 background in water Cherenkov detector is also under study. ●

  20. Survival probability 1 nm + n m + p Neutrino cross section Dm2=2.5x10-3eV2, sin22q=1.0, L=295km P(nm nm) 0 0 1 2 3 4 5 nm + N m + p’s + N’ En quasi-elastic scattering Requirements for Neutrino Energy The oscillation probability is maximum for En = 0.5~1.0 GeV ● Neutrino energy is calculated from quasi-elastic scattering; ● They are recognized as single ring muon events in SK, and neutrino energy can be calculated by simple 2-body kinematics. Neutrino interactions with p productions are background to select quasi-elastic scattering. ● Fraction of quasi-elastic scattering is smaller for high energy neutrinos. Neutrinos of En=0.5~1.0GeV are desired.

  21. SK beamline q 1° 2° 3° 0° Off Axis beam The center of the beam direction is adjusted to be 2o ~ 3o off from the SK direction. Although neutrino intensity at SK is lower, the peak energy is low and high energy neutrinos are suppressed. ● We want to adjust the peak energy to the oscillation maximum, ● which has still large uncertainty. Keep a tunability of the beam direction and wait other experiments.

  22. 2.0o HK SK 2.0o 2.5o 3.0o Beam eye Tunability of the beam direction and shape of the decay pipe Hyper-Kamiokande is proposed to construct about 10km away from SK. The beam direction can be adjusted to 2o ~ 3o off both from SK and HK. ● To satisfy this condition, the cross section of the decay pipe should be rectangular, and the height of the pipe is larger in downstream. ● Map in Kamioka SK ~10km Side view of decay pipe HK

  23. SK q ● 2km detector A water Cherenkov detector is definitely needed as a front detector. ● Neutrino beam intensity is too high. The rate is 60 events/spill/1kt at the 280m detector site. ● 110m of neutrino production point must be viewed as “point like” for reliable flux extrapolation to SK. ● Construct a water Cherenkov detector at an appropriate distance. ● 2km detector Muon range counter Water Cherenkov Fine grained detector 2km target

  24. Summary Super-Kamiokande After the recovery in December 2002, Super-Kamiokande-II is successfully in operation. ● K2K The experiment has taken data corresponding to more than 70x1018 p.o.t. Data-taking will continue at least until March 2005. ● Analysis based on 1999-2001 data (47.9x1018 p.o.t.) was published. ● Probability of null oscillation is less than 1% Dm2 ranges (1.5~3.9)x10-3eV2for sin22q=1.0@90%C.L. JHFn Complete understanding of neutrino mass matrix ● Hopefully, start in 2009. ● Keywords: ● ne appearance for q13 measurement ~100 x K2K Off-axis beam 2km detector

  25. Milestones of Super-Kamiokande, K2K and JHFn SK-I Since Apr. 1996 SK-II SK accident Half recover SK-III Full recover K2K-I K2K-II JHFn construction JHFn Today

  26. SUPPLIMENT

  27. nm + n m- + p ? A typical K2K neutrino event in Super-Kamiokande

  28. Detector upgrade in K2K-II For more precise study of neutrino interactions in sub-GeV range, a new detector SciBar has been installed. ● Full active solid scintillator tracker. ● 14400 channels of 1.3cm x 2.5cm x 3m scintillator bar which contain wavelength shifting fibers inside. Even short track of less than 4cm can be recognized. ●

  29. END

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