A VLBL experiment to Measure CP, sin 2 2  13 and  m 2 23 sign Yifang Wang

Content Why LBL Optimum baseline ? Physics potential A detector design

We Know Now |  m 2 32 |, sin 2 2  SuperK  m 2 21, sin 2 2  KamLAND,SNO We Want to Know in future  sin 2 2  13, ±  m 2 32,    Daya Bay factory/beam

What is the optimum baseline ? Y.F. Wang et. al, PRD Phys. Rev. D65 (2002)

A. Malensek, Fermilab note FN-341; M. Bonesini et al., EPJC20(2000)13

T2B and T2K: complimentary Y-F. Wang et al., Phys. Rev. D65 (2002)

T2B and T2K: complimentary Aoki, K. Hagiwara et al, PRD 67(2003)093004

Study of density effects: Lian-You Shan et al., Phys. Rev. D 68 (2003)

Detector Requirements Particle ID: e,  Pattern recognition: NC vs CC,  vs e Energy resolution: P(E ), Eff./Bkg Charge ID(only for F): wrong-sign muon LARGE MASS

Currently(Proposed) Detectors for Factory/Beam Iron Calorimeter Liquid Ar TPC Water Ring Imaging Under Water/ Ice Mass10 kt1-100 kt1kt - 1 Mt100 Mt Charge IDYesyesNo Energy range 1 GeV – 200 GeV 1 GeV- 10 GeV 5 MeV – 5 GeV 15 GeV – 10 TeV ResolutionGoodVery good goodbad ExamplesMinos, Monolith ICARUS LANNDD SuperK, Uno HyperK Amanda, IceCube A MT magnetized detector at M/kt ?

Water Cerenkov Calorimeter Dimensions: 40  20  125 m 3 Each cell: 1  1  10 m 3 10,000 tanks => 100Kt Segmentation to be optimized depending on the beam, experimental hall, price,... Y.F. Wang, NIM. A503(2003)141

PVC Water tanks with Reflective lining, viewed by two 8” PMT/tank Cerenkov light yield: 20,000 photons/meter For 20 m attenuation length, 90% reflection eff. Light collection eff. 20% Cone collection eff. 10% PMT Quantum eff. 20% Total 0.4% For through-going muons, 80 PE/Tank 1 m water = 2.77 X 0 = 1.5  0

Typical numbers 30  10  300 m 3 10,000 water tanks 20,000 8” PMT/readout channels 100,000 m 2 RPC 50,000 chambers

Excellent energy resolution from a homogeneous calorimeter Bias is intrinsic to Cerenkov detector, can be corrected

RPC X-Y planes for each layer 4 cm strip size A total of 4  10 5 m 2 –identify cosmic-ray events –use cosmic-muons for calibration –pattern recognition –event shape, direction –tracking for charge ID

Toroid Magnet IF P  min = 5 GeV, we need 40 cm thick steel plate as magnet for every 20 m, a total of 6 magnet segments Total magnet weight: 16 kT

Large detector with excellent energy resolution and pattern recognition capabilities Detector for  factory/beam cosmic-ray composition Supernova Search for WIMPs, verify DAMA's results Search for monopoles Search for proton decays Search for point and diffused sources Search for large scale anisotropies Search for fractionally charged particles Lots of other cosmic-ray physics

A Simple Exercise:  m 2 32 =  m 2 31 = 3  eV 2  m 2 21 = 5  eV 2 sin 2 2  32 = sin 2 2  21 = 1 sin 2 2  31 =  = 0 A = 1  eV 2 /GeV

Two Scenarios considered for the near future: A) JHF(HIPA) to Beijing L=2100 km 1300 events/100kt-Yr

B) Fermilab to Minos L=735 km 45K evts/100kt-Yr

A typical  CC event

Well reconstructed jet for e,  and good energy resolution for E

e Selection: Maximum energy in a cell

n e Selection: Longitudinal length of jet

n e Selection: Number of cells

e Selection: Transverse event size

e Selection: Transverse size at shower maxima

1m*1m*13m 尺寸的水箱模型 M.J. Chen et al., NIM accepted

Total Volume: 250K m 3

Summary LBL experiments for CP and matter effects are needed km is an optimum baseline Degeneracy of parameters can be solved by experiments at different baselines; earth density is a factor to be considered seriously Water cherenkov detector is a good choice for such an experiment