Status of E14 G.Y.Lim IPNS, KEK

E14 Experiment Step-by-step approach to precise measurement of Br( K L    ) KEK-PS E391a J-PARC E14 (Step-1) J-PARC E14 (Step-2) KL beam line sharing T1 targetUpdated E391a detector.

Large parameter space for NP

In the Step-1, Beam line with common target at the new facility. Finer segmented longer calorimeter. Neutron insensitive beam hole photon veto. To fit the high intensity environment. To establish a way to reject backgrounds and properly estimate their level. To make a realistic plan for the Step-2.

Beam line

KL Beam line

Original Plan for Beamlines S. Nagamiya 4 th J-PARC PAC

Characteristic of KL line Collimation with multi-stage thick collimator. Different situation compared to E391a. –Finite size of target image. –Start collimator far from production target. Parallel incident neutron. Affected by various materials upstream. Beam Sharing with K1.1. –Longer beam line : smaller solid angle –Larger extraction angle: better KL/n ratio, soft neutron. E391a results shows reliability of M.C. study A trial for E14

The effect of upstream materials Start KL collimator T1 target Pb absorber Scattering points to produce halo neutron Halo neutrons will be increase as a factor of 1.6 with current optimized K1.1 elements.

To avoid upstream scattering Cu collimator (additional possible source) Wide range of neutron generation at Cu. Guide line for trimming. Beam size V.S. Halo production.

Square beam To adapt target image. Beam hole of the calorimeter is square. (easy to construct) To increase KL yield. To decrease halo neutrons. We have to check –Large effective radius (B.G. level). –Effects of primary beam stability.

KL yield Depends on MC package –G4 / G3 / FLUKA  We use G4 result as a default  FLUKA may reproduce data according to production experiment (BNL-E802)

Detector up-grades

E14 Detector

Calorimeter 7.0 X 7.0 X 30 cm X 2.5 X 50 cm X 5.0 X 50 cm 3

No shower leakage We can suppress the CC02 event to extend into signal region by correct energy measurement and better position resolution. E391 Run-2 Result

Shower shape analysis Fusion rejectionAngle Measurement E391a E14 E391a

Status of preparation CsI transfer –Procedure established –1st shipping (~300) in Mar Readout R&D –125MHz FADC –Beam test in Dec 2007 Cockcroft-Walton PMT base –1st prototype in Jan 2008

Rehearsal of CsI disassembling At FNAL-KTeV hall in Dec 2007

And CsI packing

Test of CsI Readout Beam test at FNAL in Dec 2007 –Using M-Test line 125MHz FADC –16ch VME module –FPGA control  Debugging  Synchronization with usual DAQ system

Test of CsI Readout The readout worked successfully.

Beam Hole Photon Veto Insensitive to neutrons: photon detection inefficiency for E  > 1 GeV False hit rate : 2MHz Proven by prototype at the beam test

MB Upgrade Extra 5Xo for better efficiency. Studying inner extra module. - Low energy photon. - Inner module with better visible ratio.

Schedule digest

Summary E14 aims at search for the K L    with SM sensitivity. Beam line design is under studying. –Fabrication of beam line elements in FY2008. –Beam line construction and survey in FY2009. CsI Preparation –Prototype electronics was tested at FNAL on Dec –1 st transferring process is being done on Feb. and March, –Assembling will be done in Back ground estimation is up-dating. –Continuously debugging and developing GEANT4-base M.C. Aiming at engineering run in 2010.

Back-ups

Comparison among three different configurations. ‘KL line alone’ reduces N_halo/N_KL as factor of 3.3 compared to that of ‘original K1.1’. ‘Modified K1.1’ recovers N_KL, however the number of halo neutrons is still larger as factor 1.6 compared to that of ‘KL line alone’. - We need to check feasibility to make large holes (r=2.5cm) in K1.1 magnets.