K Physics at J-PARC - INFN · 2005-05-31 · Outline [in the next 16 slides, 15 minutes] • “hadron-machine” experiments in Japan – KEK 12GeV PS (1977 – 2005) – J-PARC

K+ Physics at J-PARC

Takeshi K. Komatsubara (KEK-IPNS)

2005.May.26 K - RARE Meeting at INFN, Frascati

Takeshi K. Komatsubara (KEK-IPNS) 1 K+ Physics at J-PARC

Outline [in the next 16 slides, 15 minutes]

• “hadron-machine” experiments in Japan

– KEK 12GeV PS (1977 – 2005)

– J-PARC (2009 –)

∗ Accelerators

∗ Hadron Experimental Facility

• “K+-decay at rest” program at J-PARC:

– FCNC rare decay K+ → π+νν̄

– T-violation in K+ → π0µ+ν, K+ → µ+νγ


12GeV KEK-PS experiments, by 2005

- K2K (long-baseline ν): data taking completed

- E391a (K0L → π0νν̄): Run-3 in the autumn ?

- some nuclear experiments are scheduled.

Fast Ext Slow Ext

t o

ν Beamline East Hall

North Hall

protons per pulse 6.5 2.5 ×1012

beam spill 1.1 micro 2.0 sec

cycle every 2.2 every 4.0 sec

operation in a year 6 2∼4 months


Japan Proton Accelerator Research Complex

JAERI and KEK Joint Project

(Japan Atomic Energy Research Institute)

• at the Tokai site of JAERI

• 70km north of Narita Airport,

• 50km northeast of KEK,

80 minutes to drive

• KEK “Tokai campus” was

established (April 2005)




Hadron Exp. Facility

Neutrino Exp. Facility


J-PARC 50GeV-PS operation (Slow Ext)

KEK-PS AGS J-PARC

Phase-1 (mod ?)

proton energy 12 24 30 30 GeV

protons per pulse 2.5 65 200 100 1012/spill

cycle 4.0 6.4 3.42 >4.42 sec

average current 0.1 1.63 9.5 <3.6 µA

beam spill 2.0 4.1 0.7 >1.7 sec

duty factor 50 64 20 >39 %

instantaneous rate 1.3 16 286 <59 1012/sec


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K-decay lines: KL line at 16deg and K1.1 line(S-type)

or, in the future ...Takeshi K. Komatsubara (KEK-IPNS) 10 K+ Physics at J-PARC

The show must go on !

• theoretical motivation:

|Vtd| in the SM, or beyond the SM

• impetus for more measurements:

3 events with small (and controlled) bgd,

B.R. = (1.47+1.30−0.89)× 10−10

• “K+ decay at rest” (low-energy K+):

established and matured with some known

limitaions (acceptance, ..)

• potential major upgrades have been

discussed since late 80’s

(KAON, AGS-2000, ...)


detector: solenoidal spectrometer

COLLAR COUNTER

RANGE STACK

TARGET

END CAP VETOγ

DRIFT CHAMBER

RANGE STACK STRAW CHAMBERS

CERENKOV COUNTER

BEAM CHAMBER 1

BEAM CHAMBER 2

BE-O DEGRADER

END CAP VETOγ

B4 COUNTERS

COLLAR COUNTER

BARREL VETO γ

MICRO COLLAR

K+

π+

BARREL VETO γ

detector R& D’s around KEK, including:

• active degrader (PbWO4, ..)

• Silicon Strip beam counter

• “chopped” plastic-scintillators

• 500-MHz waveform digitizers


New Spectrometer for breakthroughs (conceptual stage)

≥2 Tesla spectrometer

• momentum resolution

• “compact” detector

– “fiber” stack

– “crystal” barrel

• segmentation

goal: more than 50 SM signal events (BR precision ≤ 20%)


T-violating PT in K+ → π0µ+ν, K+ → µ+νγ

PT• PT ≡ sµ+ × (pπ0 × pµ+)

|pπ0 × pµ+ | : T-odd

→ an observable of CP violation

• sensitive probe of non-SM CPV

• PT = −0.0017 ± 0.0023stat ± 0.0011syst

( |PT | < 0.50% )

Kµ3 from KEK-E246: PRL 93(2004) 131601


J-PARC T-violation experiment (K+ decay at rest)

C3C4

CsI (Tl)

Polarimeter

(a)

µ+

K+

C- Counter

Pb

C2

0 0.5 1m

TOF

v

Quad

-10 -5 0 5 10 y (cm)

µ stopper Trigger counter

TOF counter

C4 chamber

Left e counters Right e counters+ +

Fe field trim

+e+

µ+

Cu degrader

z

y

r

z

(or y)

r

Target

µ stopper

Cu degrader

(b) (c)

counter

stopperIron pole

Coil

Target

CsI (Tl)

e+

+µ

e counter+

+

Magnet

r

(or y)z

upgrading the E246 apparatus, in an early stage of J-PARC:

• CsI(Tl) readout

• photon veto system

• additional tracker

• polarimeter system


New Detector for breakthroughs

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+µ

+

Calorimeter

Preshower detectors

Degrader

Active targetK

Central tracker

Veto counters

Trackers

γ

γ

γ

Polarimeter

-veto and calorimeter

+e

+µ

TRACKER

Plastics

Al-plates

ACTIVE POLARIMETER SEGMENT

MWPC

goal: PT ∼ 10−4 (E246 was limited by the statistics)


NP Experiments at J-PARC: near-term schedule

2003 Jan 30 LoI’s were submitted.

Jun Facility Committee’s assessment:

- Day-1 experiments

- Phase-1 experiments (including kaon experiments)

2004 Feb Report on the Beamline Layout plan of the Hadron Exp Hall

http://www-ps.kek.jp/jhf-np/Layout/Layout.html

2005 Jun ? Call for full-Proposals

2006 Mar ? deadline of the Day-1 Proposals

2008 J-PARC first beam ??

2009 Day-1 experiments start ??


Summary : K+ Physics at J-PARC

• new Hadron Experimental Facility, under construction

• “K+-decay at rest” experiments, with established techniques

to control backgrounds, systematics.

• K1.1 line for lower-energy K+ beam (studies in progress),

or new K+ beam line in future

• goal: beyond the Standard Model with K+ decays


Backup Slides


KEK-PS BNL-AGS FNAL/CERN

1960 Experiments started (32GeV).

1964 (the year I was born) K0L → π+π−

1977 Experiments started (12GeV).

E10: K+ → π+νν̄

E89,104: K+ → µ+νH

E99,195: PL in K+ → µ+ν

E137: K0L → µe ←→ K0

L → µe direct CPV: ε′/ε

K+ → π+µ+e− K0L rare decays

K+ → π+νν̄ K0S decays

1993 Booster

E162: K0L → π+π−e+e−

E246,470: PT in K+ → π0µ+ν, ..

E391a: K0L → π0νν̄

* 1992∼ US-Japan kaon program (BNL-E787/E949, FNAL-KTeV)


K0.8/K1.1 line(C-type) and high-memontum line


Documents

K Physics at J-PARC - INFN · 2005-05-31 · Outline [in the next 16 slides, 15 minutes] • “hadron-machine” experiments in Japan – KEK 12GeV PS (1977 – 2005) – J-PARC