P. Strasser

A search for deeply bound kaonic nuclear states

Abstract We have measured proton and neutron energy spectra by means of time-of-flight (TOF) from 4He( K stopped − , p / n ) reactions (KEK PS E471 experiment). In the proton spectrum, a clear mono-energetic peak was observed under semi-inclusive condition, which was assigned to the formation of a strange tribaryon S0(3115) with isospin T = 1 . The mass and width of the state were deduced to be 3117.7 −2.0 +3.8 ( syst . ) ± 0.9 ( stat . ) MeV / c 2 and 21.6 MeV / c 2 , respectively, and its main decay mode was Σ N N . In the neutron spectrum, a mono-energetic peak was found as the result of a detailed analysis, which was assigned to the formation of another kind of strange tribaryon S+(3140). The mass and width of the state were deduced to be 3140.5 −0.8 +3.0 ( syst . ) ± 2.3 ( stat . ) MeV / c 2 and 21.6 MeV / c 2 , respectively, and its main decay mode was Σ ± N N . The isospin of the state is assigned to be 0. The results are compared with recent theoretical calculations.

Proposal for X-ray spectroscopy of muonic atoms formed from implanted ions in solid hydrogen films

A new method is proposed to extend muonic atom X-ray spectroscopy to the study of nuclear beams, including radioactive beams, by stopping both muon and nuclear beams in a solid hydrogen film. The muon transfer reaction to higher Z nuclei is used then to form muonic atoms. This method would allow studies of the nuclear charge distribution of unstable atoms.

Slow muon experiment by laser resonant ionization method at RIKEN-RAL muon facility

b Abstract We report first results of the slow muon generation from pulsed surface muon beam using a method of resonant laser ionization of muonium. The muonium is produced from the muon beam by electron capture near the surface of thin tungsten foil heated to 2100 K. The ionization is resonantly enhanced by using a vacuum-ultraviolet (VUV) radiation resonant with 2P state of muonium (l s122.09 nm). A pulsed beam at 355 nm is used for an efficient 1S-2P ionization from the 2P state. The VUV beam with pulse duration of 4 ns and with bandwidth of over 100 GHz to match the Doppler broadening of muonium (200 GHz) is generated by resonant third-order sum-difference frequency conversion (v s2v yv ) in krypton gas phase-matched with argon buffer gas. The v beam has been tuned to VUV R T R the two-photon resonance of 4p 5pw1y2,0x state in krypton to enhance the conversion process. Yield of the VUV 5

Experimental setup for X-ray spectroscopy of muonic atoms formed from implanted ions in solid hydrogen

Abstract An experimental setup comprising of a cryogenic target and an ion implantation system has been constructed to perform muonic X-ray spectroscopy with muonic atoms formed from implanted ions in solid hydrogen films. Gaseous mixtures of hydrogen (H2) and deuterium (D2) have been frozen onto a thin 60-mm diameter silver foil, and then irradiated with charged particles of energies up to 33 keV /q . Already, solid films of H2 and D2 mixtures with implanted helium ions have been successfully used in muon catalyzed fusion related experiments at RIKEN-RAL Muon Facility. This new method allows studies of the nuclear charge distribution of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available.

µCF experiments in thin deuterium films and progress towards slow µ− production

Muon-catalyzed fusion was investigated in thin solid deuterium films to determine the experimental feasibility of slow µ− production by detection of dd fusion protons as well as slow µ− collection utilizing a large-acceptance magnetic spectrometer. The spatial distribution of the fusion reaction in the film was extracted, and an optimum thickness for slow µ− emission was deduced. Collected 10 keV µ− were also successfully detected. However, the dd fusion yield being insufficient, we were not able to distinguish slow µ− via µCF from degraded µ−.

Muon catalyzed fusion experiments on muonic deuterium atom deceleration in thin solid deuterium films

Abstract Muon catalyzed fusion was investigated in a series of thin solid deuterium films by detecting protons from dd fusion. Two different contributions to the total fusion yield resulting from dμ atoms emitted from a primary hydrogen layer and from incident muons directly stopped in the deuterium film itself were observed. The thickness dependence of the fusion yield suggested the importance of molecular effects in dμ elastic scattering in D 2 .

Ultra Slow Muon Project at J-PARC, MUSE

The muon science facility (MUSE), along with the neutron, hadron, and neutrino facilities, is one of the experimental areas of the J‐PARC project, which was approved for construction at the Tokai JAEA site. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Construction of the MLF building was started in the beginning of 2004, and first muon beam is expected in the autumn of 2008.As a next step, we are planning to install, a Super Omega muon channel with a large acceptance of 400 msr, to extract the world strongest pulsed surface muon beam. Its goal is to extract 4×108 surface muons/s for the generation of the intense ultra slow muons, utilizing laser resonant ionization of Mu by applying an intense pulsed VUV laser system. As maximum 1×106 ultra slow muons/s will be expected, which will allow for the extension of μSR into the field of thin film and surface science.

Development of elemental analysis by muonic X-ray measurement in J-PARC

Muon irradiation and muonic X-ray detection can be applied to non-destructive elemental analysis. In this study, in order to develop the elemental analysis by muonic X-ray measurement we constructed a new X-ray measuring system in J-PARC muon facility. We performed muon irradiation for Tempo-koban (Japanese old coin) for test experiment of elemental analysis. Muonic X-rays originating from muon transition in muonic silver and gold atoms were identified. The contents of Tempo-koban (Au:56%) was determined by muonic X-ray intensities.

Measurement of Muonium Hyperfine Splitting at J-PARC

J-PARC K. S. Tanaka1,3, M. Aoki4, H. Iinuma2, Y. Ikedo2, K. Ishida3, M. Iwasaki3, K. Ueno2, Y. Ueno1, T. Okubo2, T. Ogitsu2, R. Kadono2, O. Kamigaito3, N. Kawamura2, D. Kawall8, S. Kanda2,6, K. Kubo7, A. Koda2, K. M. Kojima2, N. Saito2, N. Sakamoto3, K. Sasaki2, K. Shimomura2, M. Sugano2, M. Tajima1, D. Tomono9, A. Toyoda2, H. A. Torii1, E. Torikai5, K. Nagamine2, K. Nishiyama2, P. Strasser2, Y. Higashi1, T. Higuchi1, Y. Fukao2, Y. Fujiwara6, Y. Matsuda1, T. Mibe2, Y. Miyake2, T. Mizutani1, M. Yoshida2, and A. Yamamoto2

Generation and investigation of radioactive muonic atoms in solid hydrogen films

Abstract At RIKEN-RAL muon facility, a concept project is under way to extend the standard technique of muonic atom spectroscopy to the use of radioactive isotope beams. This new method would allow studies of the nuclear properties and nuclear sizes of very exotic nuclei at facilities where both intense negative muon and radioactive nuclear beams would be available. The present status of a feasibility study is being reported.