P. Kitching

Evidence for the decay K+ ---> pi+ neutrino anti-neutrino

An event consistent with the signature expected for the rare kaon decay K+ --> pi+ nu anti-nu has been observed. In the pion momentum region examined, 211 pi+ nu anti-nu, the branching ratio is (4.2 +9.7/-3.5) x E-10.

Systematics of the excitation of M1 resonances in medium heavy nuclei by 200 MeV proton inelastic scattering

Abstract In a series of seventeen nuclei ranging from 51 V to 14 Ce, broad resonance structures are observed at energies between 8 and 10 MeV, nearly mass independent. These resonances have very forward peaked angular distributions which imply that they are populated by an angular momentum transfer of zero. This together with the observed excitation energies suggests an M1 character for these resonances. In 51 V, 58 Ni, 60 Ni, 62 Ni, a sharp peak located at an excitation energy above the threshold for neutron emission is interpreted as a part of the T 0 + 1 component of the M1 resonance. Cross sections are given for all the M1 resonances. For 58 Ni, 90 Zr, 92 Mo, 120 Sn and 140 Ce, an “attenuation” factor for the cross sections is extracted in a DWIA calculation assuming simple shell-model structures for these resonances.

Improved measurement of the K+ ---> pi+ nu anti-nu branching ratio

An additional event near the upper kinematic limit for K+ to pi+ nu nubar has been observed by Experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+ to pi+ nu nubar)= 1.47 (+1.30, - 0.89) x 10-10 based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

New measurement of the K+-->pi+ nunu branching ratio.

A.V. Artamonov, B. Bassalleck, B. Bhuyan, ∗ E.W. Blackmore, D.A. Bryman, S. Chen, 4 I-H. Chiang, I.-A. Christidi, † P.S. Cooper, M.V. Diwan, J.S. Frank, T. Fujiwara, J. Hu, J. Ives, D.E. Jaffe, S. Kabe, S.H. Kettell, M.M. Khabibullin, A.N. Khotjantsev, P. Kitching, M. Kobayashi, T.K. Komatsubara, A. Konaka, A.P. Kozhevnikov, Yu.G. Kudenko, A. Kushnirenko, ‡ L.G. Landsberg, § B. Lewis, K.K. Li, L.S. Littenberg, J.A. Macdonald, § J. Mildenberger, O.V. Mineev, M. Miyajima, K. Mizouchi, V.A. Mukhin, N. Muramatsu, T. Nakano, M. Nomachi, T. Nomura, T. Numao, V.F. Obraztsov, K. Omata, D.I. Patalakha, S.V. Petrenko, R. Poutissou, E.J. Ramberg, G. Redlinger, T. Sato, T. Sekiguchi, T. Shinkawa, R.C. Strand, S. Sugimoto, Y. Tamagawa, R. Tschirhart, T. Tsunemi, ¶ D.V. Vavilov, B. Viren, Zhe Wang, 3 N.V. Yershov, Y. Yoshimura, and T. Yoshioka

Study of the decay K+→π+νν̄ in the momentum region 140<Pπ<199MeV/c

Experiment E949 at Brookhaven National Laboratory has observed three new events consistent with the decay K+ => pi+,nu,nubar in the pion momentum region 140 pi+,nu,nubar events to seven. Combining this observation with previous results, assuming the pion spectrum predicted by the standard model, results in a branching ratio of (1.73+1.15-1.05)e-10. An interpretation of the results for alternative models of the decay K^ => pi+,nothing is also presented.

The elastic scattering of intermediate energy protons from 40Ca and 208Pb

Abstract Elastic scattering of protons from 40 Ca and 208 Pb has been studied using the MRS facility at TRIUMF. Cross section and analyzing power ( A y ) angular distributions to 50° in the center of mass have been measured for incident proton energies of 200, 300, 400 and 500 MeV. Comparisons of the experimental results are made with calculations based on relativistic and non-relativistic phenomenological models, and with relativistic and non-relativistic microscopic models. The differences between the results of the non-relativistic and relativistic models manifest themselves in the spin observables. They are found to be smaller in the phenomenological approach than in the microscopic one and they depend on energy.

Two-body pion production d(p, π+)t AT 470 and 590 MeV

Abstract The differential cross section for the reaction d(p, π + )t has been measured for c.m. angles between 37° and 160°, at incident proton energies of 470 and 590 MeV. The results are in qualitative agreement with the predictions of a two-nucleon model of the reaction when the D-state contribution is included, except for the existence of a backward peak at 470 MeV. Other models of the reaction are discussed; none of them gives a rationale for the backward peak at 470 MeV. A similar peak is present in older data at 325 MeV.

Quasi-free scattering of polarized protons☆

Abstract Cross section and analyzing power, energy-sharing spectra have been measured for the 16 O( p , 2p) reaction at an incident energy of 200 MeV for twenty-four different pairs of angles of the detected final-state protons. This general survey is intended to test the validity of the distorted wave impulse approximation (DWIA), particularly with respect to the predicted j -dependent analyzing power caused by the distorting optical potentials and nuclear spin-orbit coupling. Although the data in general confirm this j -dependence, agreement in detail between DWIA calculations and the analyzing power data becomes worse as the momentum of the recoiling nucleus increases. Predictably, the cross-section calculations show more sensitivity to the optical-model parameters than do the analyzing powers. Within the present limits imposed by scanty elastic scattering data, there seems to remain a choice between predicted ( p , 2p) cross sections which either are unreasonably large or which have the incorrect energy-sharing shapes. More comprehensive elastic scattering and total reaction cross section data are clearly needed.

Further search for the decay K+ ---> pi+ nu anti-nu in the momentum region P < 195-MeV/c

We report the results of a search for the decay

Measurement of the muon decay parameter {delta}

K^+ \to \pi^+ \nu \bar \nu