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Status of E391a experiment for the rare decay. October 3, 2005 @ ICFP 2005 Takao INAGAKI ( KEK) for the E391a collaboration. Theoretically it is very pure and clean, but it is a very rare decay. Possible Scenario. - PowerPoint PPT Presentation
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October 3, 2005 @ ICFP 2005
Takao INAGAKI ( KEK)
for the E391a collaboration
Status of E391a experiment for the rare decay
Theoretically it is very pure and clean, but it is a very rare decay
Recently confirmed that the theoretical uncertainty is also very small in most of calculations of new physics. hep-ph/050517
Possible Scenario
Experimentally very challenging
• Small branching fraction
Any tiny effects are possible sources of background
• Weak kinematical constraint (a
ll neutrals, three-body decay with invisible neutrinos, etc) Not easy to separate the signal from background
This is the reason why the present limit stays at 5.9X10-7 (KTeV, 2000) and why E391a is the first dedicated experiment in spite of a theoretically dream channel.
Strategy: step-by-step approach
E391a at KEK 12 GeV PS O(10-10)
An experiment at JPARC 50 GeV PS O(10-14)
Collaboration and status of E391a
● The third data taking (Run-III) is scheduled in Nov/2005
• E391a collaboration • 11 institutes, ~50 members from 5 countries
Univ. of Chicago, JINR, KEK. Kyoto Univ., NDA, National Taiwan Univ.,
Osaka Univ., Pusan National Univ., RCNP, Saga Univ., Yamagata Univ.
• Status of experiment • First data taking was carried out from Feb/2004 to July/2004
• Second data taking (Run-II) was carried out from Feb/2005 to April/2005
0.25 GeV/c
0.13 GeV/c
Three important tools
Additional discussion about detection inefficiency, which causes photon veto miss
・ The inefficiency strongly depends on gamma energy. It is large at low energy
↓
Hi gh PT selection
・ The inefficiency strongly depends on the detection threshold
↓
Low detection threshold
Concern : how we can lower it under high rate environment. Understand the detector response at low energy deposit.
Final plot
Using 10% sample of Run-1
What we have learned
BackgroundBy understanding the sources of side-band events
Core neutron
Halo neutron
Kpi2: negligibly small
Back splash
It is clearly observed for the main barrel having both-end readout.
Mean time
Tim
e d
iffere
nce
(p
ositio
n)
Introduction of J-PARCour next playground
Configuration of the accelerators
NeutronMuon
Layout
K0 line is included in the construction plan
Construction Schedule
Linac
3 GeV
50 GeV
Materials + Life
Nuclear-Particle
Neutrino (plan)
Others
Salt Farms
Bldg. construction
Equip. constructionBeamtest
Bldg. construction
Equip. constructionBeamtest
Bldg. construction
Equip. constructionBeamtest
Bldg. construction
Equip. constructionBeamtest
Bldg. construction
Equip. constructionBeamtest
Bldg. construction
Equip. constructionBeamtest
Construction
Archelogical studies
Construction Schedule (as of Oct., 2003)
FY2001 FY2002 FY2003 FY2004 FY2005 FY2006 FY2007 FY2008
BeamConstruction Start
study report
Summary
1. is one of the pure and clean channels in the field of quark flavor physics. It provides a critical and unambiguous check of the Standard Model.
2. E391a, which is the first dedicated experiment, has started at KEK 12-GeV PS successfully.
3. Using 10 % sample of Run I, we obtained a new limit of 2.9×10-7 (90%cl).
4. We are learning many things, background sources, the rate of extremely low energy deposit etc. They must be quite important for a future extension.
5. J-PARC, which is expected to be our next play-ground, is now being constructed steadily. We are preparing a proposal.