US-Japan and the KTeV Research Program at Fermilab

US-Japan and the KTeV Research Program at

Fermilab

R. TschirhartUS-Japan 30th Anniversary Symposium

Kona, HawaiiOctober 20th 2010

US-Japan 30th Anniversary Symposium October 20th 2010 R. Tschirhart - Fermilab

Kaons at the TeVatron• The KTeV experiment was primarily

a comprehensive study of neutral kaon decays, data collected 1996-2000.

• The research program yielded 32 PhD theses and 50 physics publications, most notably the establishment of matter/antimatter asymmetry in particle decay amplitudes.

• This rich research program was largely driven by intense beams of in-flight neutral kaon decays reconstructed with a high-speed , high-resolution spectrometer.


Context and Prejudice: Flavor Physics in the early

1990’s • Neutrino mixing out of reach??

• What is CP violation? Why is it so small? A new super-weak force??

• The top quark is elusive…..very high mass; does it even exist?

• If the top quark exists and is heavy…new high mass particles can compete in virtual loops in flavor changing neutral currents.

• But…B meson’s are reconstructed only by the handful.

• K mesons can be produced in large numbers, but how can we possibly measure the rare KLgp0p0 neutral mode decay with sufficient precision to search for direct matter anti-matter asymmetries??


Fast forward…Highlights of KTeV

Science…• Re(e’/e) = (1.66 ± 0.26)×10-3*

• KLg p0ee, p0mm

G(K0→p+p-) - G(K0→p+p-) G(K0→p+p-) + G(K0→p+p-)

= (5.04 ± 0.22) ×10-6 **

Matter/Antimatter asymmetry in a decay amplitude established, Superweak model excluded.Large component of this asymmetry might arise from New Physics.

KTeV limited these rates to x8 and x25 the Standard model rates (10-11 level) for the ee and mm modes….fertile hunting ground for new physics models. * PDG, **J Imazoto

Insert piee/pimumu plot here


Serendipity: Resolution of the Vud/Vus/Vub non-Unitarity tension by precision measurement of KLgpen

decays.

Enrico Lunghi, LME-2010, Fermilab

2010: KTeV,BNL-865,NA48,KLOE

New Physics models squeezed out beyond the 5 TeV scale

2004: |Vud|2+|Vus|2+|Vub|2 < 1 ??


…Our competitors and colleagues…


Emergence of the “Flavor Problem”

Why don’t we see the Terascale Physics we expect affecting the flavor physics we study today??

4


KTeV was the culimanation of the high-energy in-flight program at

Fermilab

University of Chicago Group


Enabling Collaboration!

1996 KTeV Collaboration meeting at the University of Arizona.

75 collaborators, 32 PhD students, 50 science publications.


US-Japan Contributions to KTeV: Unprecedented

photon calorimetry and Trigger & DAQ

Beam view of K0gp0p0 in CsI calorimeter


KTeV Pure CsI Calorimeter

• 3100 crystals, 1.9mx1.9m

• 27 X0 deep (50cm)

• 90% of light has 20-nsec component

• Osaka group and US-J developed “collar” veto systems that cleanly defined acceptance.


Calorimeter Readout

• 5-6 Stage low-gain (x3000) PMTs critical to preserve large dynamic range. Developed by Osaka, Fermilab, and UCLA (Arisaka-san) working closely with Hamamatsu.

• PMTs funded by US-Japan.

• QIE: 16-bit range-

compressed charge integrating pipelined readout (9-bit resolution) operating at 53 MHz local to PMT base, developed by FNAL.


Delivered EM-calorimetry performance better than 1%

resolution over full physics energy range: Best in the field


KTeV CsI Crystals and PMTs continuing great science in the

JPARC E14 KLgp0nn adventureJPARC PAC tour of E14 calorimeter

E14 Calorimeter assembly

KTeV Calorimeter assembly


US-Japan largely funded the visionary DAQ that was first in the field to filter

out most events based on full reconstruction

Great science needs great throughput!

Visionary effort led by Yamanaka-san and Nakaya-san


The US-Japan@KTeV Legacy

• Established decay-amplitude matter-antimatter asymmetries together with our CERN colleagues.

• Probed many, many rare-decays that have cranked up the tension on the “flavor problem”.

• Substantially advanced the state of the art in precision calorimetry and data acquisition in High Energy Physics.

• Developed next generation leaders in flavor physics and elsewhere.

Ichiro Suzuki, Seattle Mariners: ( 鈴木一朗 )

Best player in the league-Achieved through systematic high quality team-work and

leadership on the field


Spares


Osaka Unviersity PhDs

• “Study of the Decay KL->pi+-e-+nu e+e- to Probe the Semileptonic K-pi Structure” by Katsushige Kotera, Osaka University, September, 2006.

• "CP Asymmetry in the Decay KL-> pi+pi-e+e-" by Katsumi Senyo, Osaka University, December, 1999.

• "Search for the Decay KL ->pi0 mu+ mu-" by Masayoshi Sadamoto, Osaka University, February 1999.

• "Search for the Decay KL->pi0 nu nu-bar" by Kazunori Hanagaki, Osaka University, August 1998.



Documents

US-Japan and the KTeV Research Program at Fermilab