Overview of Particle Physics Experiments In the-35 -year

Overview of Particle Physics Experiments In the-35 -year History of KEK-PS Yorikiyo Nagashima Osaka University Jan. 22, 2008 PS REVIEW 080122 1

Historical Background of PS construction. Pre-history of PS Options discussed 1937: 1 st Cyclotron at RIKEN , Osaka U. • 12 Ge. V; high intensity 1943: 60 inch Cyclotron (2 nd to Berkeley) • 40 Ge. V; conventional 1941 -45: World War II • 80 Ge. V; cascade 1945: Destruction of the cyclotron. Reconstruction banned by the Occupation Army 1952: Peace Treaty ; the end of Occupation 1956: Electron Synchrotron started (0. 75 1. 3 Ge. V) History of PS Construction 1958: Discussion started 1962: Proposal of PS 1964: Preliminary approval 1966: 12 Ge. V 40 Ge. V Big debate in HEP community. 1970: 40 Ge. V 8 Ge. V, ¼ budget , ¼ manpower Big debate in the academic community Dumping the cyclotron in Tokyo bay 1971: Construction started. 1977: Beam commissioning (8 12 Ge. V) PS REVIEW 080122 2

Progress of Particle Physics in Japan Discovery of the Electro-weak Theory 　　 The Standard Model Established Infancy　　　　　 Youth　　　　　 Maturity JPARC PSI：　 Training Period. 　　　　　　　　 +International Collaborations PSII：　 Frontier for NP, Survival for Particle Physics +TRISTAN PSIII：　A New Frontier and World Leading Expts. (n-oscillation, K-decays) +KEKB, SK PS REVIEW 080122 3

1 st Experiments: 1 m Bubble Chamber p. N Reactions Counter Experiments; E 19, E 21 Bubble Chamber; E 6 , E 12 E 19: K. Miyake: p-p Charge Exchange Scattering M A BE Polarized Tgt. MAGNET TARGET BEAM R. Kajikawa: 080122 PS REVIEW E 21: pp Elastic Scattering 4

ICHEP 78, Tokyo, Japanese Debut in HEP club. Summary Talk by Y. Nambu The Standard Model was firmly established in this conference. PS REVIEW 080122 5

PS Review ’ 81 after 4 years of Operation By Nambu, Kitagaki, Yamaguchi Significance Purpose Problem PS REVIEW 080122 6

Polarized Target Special Features circa 1975 that were hoped to make the late comer PS competitive. High Quality Low Energy Separated Beams For Precision Data and Decays K 2 Pol. Tgt. aimed at performing Precision Hadron Dynamics And also Bubble Chamber Later K 3 1978 Horizontal Type He 3 -He 4 Dilution Refrigerated PS REVIEW 080122 7

A Track of PS from Particle Physics Point of View (1 a) PS-Ia: 1977 -78 Significance: Training and Obtaining Self-confidence Debut in HEP Society at ICHEP’ 78 in Tokyo Strategy to make PS competitive: Pre-construction emphasis: • Resonance Hunting Precision and Hadron Dynamics 40’’ Bubble Chamber and Polarized Target Obsolete after SM was established during the construction After Beam Commissioning : Emphasis on test Exotic Resonances, Weak Decays SM • High Quality Low Energy Separated Beam Did the Strategy work ? See the Achievement in the first 10 years in advance. 10 -12 PS REVIEW 080122 8

PS　achievement in the 1 st 10 years reviewed in 1990 PS REVIEW 080122 9

The following sample are picked up entirely with my personal prejudice. My apology for not covering many works that achieved important contributions. PS REVIEW 080122 10

Experiments in the first Period PSI (1977 -84): List of Bubble Chamber Expriments in PSI (1977 -80) Exp. # Alias Spokesman Organization E 06 RES R. Sugawara KEK/Osaka City U. Study of Pion Nucleon Inelastic Scattering in the Intermediate Energy Region E 12 p. DD T. Hirose TMU, TAIT Study of π-p Three-Body Reaction with Emphasis on Diffraction E 50 DLBC T. Kitagaki Tohoku u. Tohoku Gakuin U. Nara Women's U. Direct Electrons in pp Interaction at 8 Ge. V/c E 53 p. A S. Kaneko Hiroshima U. Studies of π -- Nucleus Interaction at 4 Ge. V/c in Bubble Chamber E 57 pp. BC S. Yamamoto Tokyo U. Studies of pp Interaction in the Range of 0. 8 -2. 0 Ge. V/c E 62 pbar-p Y. Yoshimura KEK/Tokyo U. Nara Women's U. Hiroshima U. Niigata U. Study of Exotic States in p-bar p Reaction at 3 -5 Ge. V/c E 80 DPBC H. Sai Tokyo U. Measurements of dp Reaction in 2. 0 -4. 0 Ge. V/c Hadron Reactionｓ Resonance Hunting Title Decays Others • Note: The Bubble Chamber was very productive during 1960’s. So it was one of special-feature projects in the construction stage. • However, most basic resonances that contributed to the discovery of the Quark Model were already found and the emphasis shifted to exotics by the time PS started operation. • The BC without external trigger was no match against counter experiments in the field of high statistics battle, and was shut down in 1982. • Nevertheless, there were some. PS REVIEW 080122 that did well. experiments 11

An Example of Bubble Chamber Experiments E 57　S. S. Yamamoto: “An Experiment that provided a basic set of data and also excluded the existence of I=1 dibaryons(2240), (2320)” D-dominance Models including Di-Baryon s(ppp 0) s(pnp+) PS REVIEW 080122 Spires 2008 12

List of Counter Experiments (PS-I ; 1977 -84) Exp. # Alias Spokesman Organization E 10 Kdecay Y. Nagashima KEK Study of Rare Decay K +→ π+ννbar, p+axion E 19 CEX K. Miyake Kyoto U. Measurements of Differential Cross Section and Polarization for π-p →π0 n in 1. 8 -3. 0 Ge. V/c E 21 p. N R. Kajikawa Nagoya U. Measurements of Differential Cross Section and Polarization for π-p Elastic Scattering at 2 -4 Ge. V/c E 33 YN T. Kamae Tokyo U. Study of Narrow Resonance in pbar-p Reaction below 1 Ge. V/c E 34 KN F. Takasaki KEK Study of K+n↑→K+n, K 0 p and K-p↑→K 0 n Reaction E 45 DLC S. Mikamo KEK Direct Lepton Production by Proton E 49 L K. Takikawa Tsukuba U. Study of Asymmetry in Λ→ peν, pμν Decay by Hyperon Beam E 63 CEXH K. Miyake Kyoto U. Measurements of Differential Cross Section and Polarization for π-p →π0 n in 1. 8 -3. 0 Ge. V/c E 64 p. I T. Tsuru KEK Studies of 2π, 3π States in π-p Charge Exchange Reaction E 68 Pbar. PC S. Kobayashi KEK Detection of Discrete γ and π 0 from p-bar p System E 74 Pbar. PR K. Nakamura Tokyo U. Baryonium in p-bar p Reaction below 1. 0 Ge. V/c E 75 PN K. Ogawa KEK Measurement of P-parameter in pn Elastic Scattering E 81 KDEL G. Igo UCLA/KEK Asymmetry in K+d and π+d Elastic Scattering around 1. 5 Ge. V/c E 83 p. D Y. Sumi Hiroshima U. Dibaryon Resonance in πD Scattering E 89 Km T. Yamazaki Tokyo U. Detection of Monochromatic μ +, e+ Associated with Heavy Neutrinos in K + → μ+v and e+ν Decay E 92 S K. Miyake Kyoto U. Measurements of Asymmetry in Σ + → pγ Decay E 99 Kmp E 104 Title + + + R. Hayano Polarization Hadron Reaction. Tokyo U. Resonance Hunting of μ in K → μ ν Decays Km. II T. Yamazaki Tokyo U. Search for Heavy Neutrinos by K μ 2 Decay Hadron Reactionｓ Resonance Hunting Decays Others 2/3 Hadronic, very little interest in Weak Decays in the beginning 13

A Flagship Experiment during the early PSI period. C-type Magnet Polarized Target Beam PS REVIEW 080122 Beam 14

E 34 results Phase Shift Analysis of the Reaction K+N KN below 1. 6 Ge. V/c PLB 112(1982)80 A kind of perfect experiment, but this one also looked for possible S=1 exotic baryons And found none. Note: Emphasis before construction was on the “Perfect Experiment” • To determine the complex scattering amplitudes precisely, • 2 Complex Amplitudes in p(K)N Scattering • Need Cross sections, Polarized target Data and Polarization of scattered particles. • To determine exact locations of the resonances, with hope to elucidate the underlying dynamics. PS REVIEW 080122 • However, QCD was established ~1973. 15

Many experiments targeted specific Resonances E 33 T. Kamae, 　E 74 K. Nakamura: “ Disproof of S-resonance(1936) claimed by several groups” Spires E 68 M. Kobayashi “Disproof of other barioniums” Dotted lines observed by B. Richter et al. , PRLB 126(1983)284 PS REVIEW 080122 Spires 2008 16

An Example of Deacay Experiments E 10 Y. Nagashima: A Table–top experiment : An extinct species of HEP apparatus PS REVIEW 080122 17

KEK/PS: E 10 BR(K+ p+nn): “World’s best limit for nearly 10 years. ” BR(K+ p+axion): “An experiment that killed the original axion. ” PS REVIEW 080122 Spires 2008 18

Another Example of Weak Decays during PSI period E 92 K. Miyake: Measurements of Asymmetry in Σ+ → pγ Decay “QCD Effect” PDG 2006 PS REVIEW 080122 19

A Track of PS from Particle Physics Point of View (1 b) Summary of PSIb: 1979 -84 Making efforts to catch up with the world level. Emphasis on intense K beams and Polarized target Hunt for exotic resonances: • Test of SM or looking for a clue BSM in weak decays: • Caveat: As the only national HE machine, the demand for PS was big. Beam delivery was not enough and approval criteria was somewhat lenient to satisfy the need of users Important Events outside KEK/PS: In 1972: In 1978: In 1979: In 1981: 16 -19 Prof. Koshiba initiated U. Tokyo-DESY collaboration. Prof. Koshiba began to construct Kamiokande. Japan-US collaboration program started (all major universities). TRISTAN was approved. PS REVIEW 080122 20

A Track of PS from Particle Physics Point of View (2) Features in PSII Period: 1985 -1998 The Main Force TRISTAN+Overseas Collaborations PS : Frontier for Nuclear Physics ( Talk by Nakai) : Survival War for Particle Physics Still behind BNL and CERN, Groped the way of Uniqueness and Originality Strategy: Ample Machine Timeafor number of Groups small Systematic Approach in series of experiments High Statistics and Precision Tests of and beyond SM Managed to produce some world competitive Results PS REVIEW 080122 21

List of Counter Experiments in PSII (1985 -98) 　 Exp. # Alias Spokesman Organization E 119 pn N. Horikawa Nagoya U. Spin Correlation Parameter A nn in pn Elastic Scattering 　 E 121 p. I-II T. Inagaki KEK Study of a Few Pion States in π-p Charge Exchange Reaction setup as p I-I E 125 DD S. Yamamoto Tokyo U. Studies of dd Interaction in the Range of 2 -4 Ge. V/c 　 E 131 Pbar-PR T. Fujii Tokyo U. Confirmation of Mesonic Resonance (1935) in p-bar p → K+K- Reaction 　 E 135 p. I-III T. Tsuru KEK Meson Spectroscopy in π-p Charge Exchange Reaction setup as p I-I, II E 136 Z 2 N. Sasao Kyoto U. Search for Long Lived Hadrons with Charge 2 　 E 137 KL T. Inagaki KEK Search for Rare Decay K L → μe 　 E 159 p. DEL N. Horikawa Nagoya U. Analyzing Power in the p↑d →pd Reaction at 3. 5 Ge. V setup as p n E 162 CP N. Sasao Kyoto U. Experimental Study of Rare K L Decays 　 E 174 RING L. Northcliff Texas A&M Ay Measurements for NN Reaction 　 E 179 hp T. Tsuru KEK Search for the ηπ Resonance with I = 1, J PC = 1 -+ setup as p I-I, III E 195 Pm J. Imazato KEK Precise Measurement of μ + Longitudinal Polarization in the Decay K+ → μ+ν 　 Hadron Reactionｓ Title Resonance Hunting Decays PS REVIEW 080122 comment Others 22

An Example of series of Experiment : “Exotic Resonance Search in pp channel” PS I Era E 64 (p. I-I) T. Tsuru PS II Era E 121 p. I-II, E 135 p. I-III, E 179 hp: T. Tsuru and T. Inagaki Studies of 2 p, 3 p States in p-p Charge Exchange Reactions. Search for the ηπ Resonance with I=1, JPC=1 -+ PS REVIEW 080122 23

Contributions in the glueball-hybrid-4 q sector. • Confirmation of IG(JPC)=0+0 -+ Resonances in hpp system known today as h(1295) and h(1405) PRL 57(1986)1296, PLB 267(1991)293 • Indication of 1 -1 -+ Resonance in hp- system known today as p 1(1400) PLB 267(1991)293 f 1(1285) Spires 2008 • Note: • h(1295) is probably a radial excitation of h. • Old i(1460) in KKp is now h(1405). • It does not fit in quark model levels and has a large gluon component. • An excellent candidate for the 0 -+ glueball in the flux tube model. • However, lattice QCD *does not favor the interpretation. • p 1(1400), having I=1 cannot be a glueball, but a possible candidate for a hybrid or 4 q state. PS REVIEW 080122 24

Another Systematic Approach: Km 2 Decay Experiments PSI Era E 89, E 104: T. Yamazaki: “Search for a Heavy Neutrino in K+ m+n, m e+nn” E 89 Spires 2008 PS REVIEW 080122 25

Km 2 Decay Experiments : PS II Era E 99 R. Hayano, E 195 J. Imazato: Search for Right-Handed Currents in the Decay Chain K+ m+n, m+ e+nn “Lower Limit on the Mass of WR As a function of mixing angle” TRIUMF E 195 setup PDG 2006 PS REVIEW 080122 26

Other Competitive Decay Experiments E 137 T. Inagaki: Search for Rare Decays KL me and KL ee “Lepton Flavor Violation” PDG 2006 E 162 N. Sasao: Observation of the decay mode KL → π+π-e+e- “CP Violating Effect + Higher Order Effect QCD” PDG 2006 PS REVIEW 080122 27

PSII Summary PSII Period: 1985 -1998 The Main Force TRISTAN+Overseas Collaborations PS : Frontier for Nuclear Physics : Survival War for Particle Physics Still behind BNL and CERN, Groped the way of Uniqueness and Originality Strategy: Ample Machine Timeafor number of Groups small A series of Experiments for Systematic Research High Statistics and Precision Tests of and beyond SM Managed to produce some world competitive Results 24 -27 PS REVIEW 080122 28

A Track of PS from Particle Physics Point of View (3) 3 rd Period: 1999 -2005 International Collaboration Frontier and World Leading Experiments (Parallel activities: BELLE and SK) Some Experiments will be continued at JPARC K 2 K T 2 K (E 11), E 391 a E 14, E 246 E 06 List of Counter Experiments in PSIII (1999 -2005) 　 Exp. # Alias Spokesman Organization E 246 　 J. Imazato KEK Search for T violation in the K + → π0µ+ν decay 　 E 362 K 2 K K. Nishikawa Kyoto U. Long Baseline Neutrino Oscillation Experiment 　 E 391 a 　 T. Inagaki KEK Measurement of the K L → π0νν-bar Decay 　 E 470 　 T. Baker IPNS Measurement of direct photon emission in K + → π+π0γ setup as E 246 Decays Title 　 Others PS REVIEW 080122 29

PS is a Front Runner in the Internationalization A Historical Event in the Japanese Culture. Genuine International Collaborative Researches ========== • E 246 (Imazato) • Japan-Russia(INR)-Canada-Korea-Taiwan • MOU between KEK-INR in 1992 • The Majority Members are from Abroad • K 2 K (Nishikawa) • K 2 K-I: Japan-US-Korea (1995) • K 2 K-II: Japan-US-Korea-Italy-France-Spain -Russia-Switzerland-Poland-Canada (2002) • The Majority Members are from abroad. • E 391 a(Inagaki) • PAC advised to strengthen the group • Japan-US-JINR-Korea-Taiwan PS REVIEW 080122 • K. Nakamura: Jan. 14, 2006 30

E 246 PDG 2006 PS REVIEW 080122 31

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E 391 a Experimental challenge; meager positive signal Use Pencil beam Detector with complete veto system High PT selection Step by step approach KEK-PS E 391 a JPARC E 391 a Detector n 1 g 1 KL g 2 n 2 PS REVIEW 080122 33

ADOPTED FROM T. SUMIDA; 070316 PS REVIEW 080122 34

• E 326 (K 2 K): World’s 1 st Long Baseline n Oscillation Experiment. • Confirmed the n oscillation discovered by Super. KAMIOKANDE. PS REVIEW 080122 35

250 km Super. KAMIOKANDE ニュ ート リノ ビー ム KEK PS REVIEW 080122 36

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The Success of K 2 K enabled us to draw a definite future plan. Neutrino Physics K 2 K T 2 KK? T 2 KR PS REVIEW 080122 EA CH 38

Ｔ２Ｋ Kamioka JPARK 1 MW 50 Ge. V PS Super-K: 50 kton Water Cherenkov ~1 Ge. V n beam 4 MW Hyper-K: 1 Mton T 2 KK　　　　 Future Plan A K K 2 K T 2 KK Beam: 1 MW 4 MW 2 Detector: Super-K Hyper-K K (50 kton 1 Mton) Split it into 2 and place one in Korea PS REVIEW 080122 39

Summary I A Track of PS from Particle Physics Point of View Pre PS : 1952 -1976: Long Hard Labor for HEP Accelerator Re-construction 1 st Period: 1977 -84 Training Period: Debut in HEP Society at ICHEP’ 78 in Tokyo Pre-construction emphasis: Resonance Hunting and Precision Hadron Dynamics a 40’’ Bubble Chamber and a Polarized Target Out-of-date after SM was established during the construction After Beam Commissioning : Emphasis on SM test Exotic Resonances, Weak Decays Pbar p barionium, K+ p+nn, p+axion, mn 2 nd Period: 1985 -1998 The Main Force TRISTAN+Overseas Collaborations PS : Groping the way of Uniqueness and Originality Systematic Approach and Precision Tests: K 0 pm, K+ m+n Nuclear Experiments 3 rd Period: 1999 -2005 Frontier and World Leading Experiments (in parallel with BELLE and SK) T in K 0 pmn, K 2 K (LBL n oscillation), CP in K 0 p 0 nn International Collaborations PS REVIEW 080122 40

Summary II KEK/PS, 15 years behind the world fronts like CERN/PS, BNL/AGS, could not expect a bright future. However, it fulfilled its primary purpose to become a partner in the world HEP society, and to educate young people who are working actively at today’s frontier. As a bonus it provided a new frontier for nuclear physics. As the second bonus, KEK/PS even produced some forefront particle physics results, including the renowned long baseline neutrino oscillation experiment. Waves of Internationalization have reached KEK/PS. The PS Experiments owe their Success to the stable operation of the Accelerator throughout its Life. The success of late time PS activities paved a road to JPARC and other future projects. 32 -35 PS REVIEW 080122 41

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