Tritium gas handling system for muon catalyzed fusion research at RIKEN-RAL muon facility

For muon catalyzed fusion (μCF) experiments at RIKEN-RAL muon facility, a tritium gas handling system for a high purity D–T target, free from ³ component, has been constructed to perform precise measurements of α-sticking probability in the μCF cycle. The system has been constructed to enable us to purify the target D–T gas by removing ³He component, to adjust the D/T mixing ratio, and to measure the hydrogen isotope components at the experiment site. The whole performance has been confirmed and a tritium gas with the inventory of 56 TBq (1500 Ci) has been operated in the system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development of the pulsed muon facility at ISIS

The ISIS pulsed surface muon facility at RAL is presently undergoing a major expansion to provide three experimental ports with simultaneous single muon pulses at 50 Hz. This upgrade, funded by the European Community (EC), is described together with recent development results which are relevant to its future scientific programme. These new beam lines are expected to be available for experiments in June 1993.     

Radio-frequency μSR experiments at the ISIS pulsed muon facility

This paper explores the use of pulsed radio-frequency (RF) techniques to remove the frequency limitations imposed on conventional transverse muon spin rotation (μSR) experiments at a pulsed muon source by the finite muon pulse width. The implementation of the 90° pulse technique is demonstrated by observing the free precession signal of diamagnetic muons implanted in polythene, the change in signal amplitude as a function of RF pulse length is plotted and the precise condition for a 90° pulse determined. The technique is evaluated by comparing measurements made using conventional spin rotation experiments to those employing pulsed RF methods. The potential for applying standard NMR multiple-pulse methods to the μSR experiment is considered and the use of two-pulse RF sequences (90° _x ?τ?90° _x and 90° _x ?τ?180° _x ) to form a muon spin echo demonstrated.     

The ISIS pulsed muon facility: Past,present and future

The pulsed muon facility at ISIS of the Rutherford Appleton Laboratory has been operational since March 1987. It is now fully scheduled for condensed matter research using polarised surface muons, atomic physics with sub-surface muons, and μCF experiments requiring negative cloud muons. The design and performance of the present beam are briefly discussed and recent improvements to the facility are described. Essential future upgrades have recently received international support and funding, which will lead to a complete facility comparable in extent to those of the continuous meson factories at PSI and TRIUMF, but with the unique advantages of the pulsed nature of the source. Such an upgraded facility will provide unprecedented opportunities for muon science at ISIS, unmatched by any other facility until the end of the decade.     

Electron paramagnetic and muon spin resonance studies in fullerenes

This article reviews the various EPR (CW, pulsed and time-resolved) and μSR studies reported in C₆₀/C₇₀/C₈₂ fullerenes. Different techniques for preparing paramagnetic C₆₀/C₇₀ species giving an EPR signal have been included. This literature survey is complete from the beginning of fullerene research (1985) up to middle 1994.     

X-ray studies on muon transfer reactions from hydrogen to helium

We have experimentally studied the muon transfer reactions from hydrogen to helium in liquid hydrogen with helium impurity concentration around 100–1000 ppm. The X-ray from the decay of (d⁴He) molecule was clearly observed in the D₂-⁴He system, whereas the corresponding X-ray was very weak in other systems such as D₂-³He and H₂-⁴He. This is well explained by the particle decay mode of the muonic molecule.     

Coupling functions for muon hodoscopes

The specific features of calculating the coupling functions for muon hodoscopes are considered. The results of calculating the main coupling functions for three versions of the primary spectra of cosmic rays (CR)—galactic CR, solar CR during proton events, and galactic CR variations during Forbush decreases-are presented. The calculations have been performed based on modeling CR propagation through the Earth’s atmosphere using the CORSIKA code. The mean and median CR energies, contributing to the muon detector counting rate, have been calculated for different zenith angles. It has been shown that muon detectors are sensitive to different energies of primary CRs for different directions.     

Laser shock XAFS studies at OMEGA facility

ABSTRACT

State-of-the-art laser facilities offer an excellent opportunity for studying materials at Mbar-Gbar pressures by dynamical compression. This paper summarizes recent experiments on EXAFS measurements of compressed solid iron up to 5?Mbar using OMEGA laser facility. The X-ray source is produced by a spherical implosion, providing enough brightness and spectral smoothness required for EXAFS measurements. The compression path is tuned by laser pulse shaping to achieve off-hugoniot states. With an anharmonic model, the density, temperature and upper limit of strength of the compressed iron are determined from EXAFS data. Prospects of XAFS study of other materials are also discussed.     

Combination of muon spin relaxation and neutron scattering studies on magnetism

We combine the results from muon spin relaxation (μSR) and neutron scattering measurements performed on the same specimen (or system) of magnetic materials. The example on a spin glassCuMn (5%) shows that the two techniques have complementary time windows for studying dynamic spin fluctuations. In combining the results, one should note that muons and neutrons probe dynamic phenomena with different wavevectors. The results on antiferromagnetic La₂CuO_4−y illustrate the difference in the spatial range of static spin correlations reflected in the μSR precession frequency and the neutron Bragg peak intensity. With the examples of CeCu_2.1Si₂, YBa₂Cu₃O_x and Bi₂Sr₂YCu₂O_8+y , we point out that μSR is a superb tool for discovering static magnetic order while neutron scattering is the unique method to determine the spin structure. We emphasize that it is very fruitful to perform μSR and neutron experiments on the same specimen and to compare and combine the results for the better understanding of magnetism of various system.     

Design of the 10 m AEI prototype facility for interferometry studies

The AEI 10 m prototype interferometer facility is currently being constructed at the Albert Einstein Institute in Hannover, Germany. It aims to perform experiments for future gravitational wave detectors using advanced techniques. Seismically isolated benches are planned to be interferometrically interconnected and stabilized, forming a low-noise testbed inside a 100 m³ ultra-high vacuum system. A well-stabilized high-power laser will perform differential position readout of 100 g test masses in a 10 m suspended arm-cavity enhanced Michelson interferometer at the crossover of measurement (shot) noise and back-action (quantum radiation pressure) noise, the so-called Standard Quantum Limit (SQL). Such a sensitivity enables experiments in the highly topical field of macroscopic quantum mechanics. In this article we introduce the experimental facility and describe the methods employed; technical details of subsystems will be covered in future papers.     

Search for lepton-flavor-violating rare muon processes

A new approach to seeking three lepton-flavor-violating rare muon processes (μ → e conversion, μ → e + γ, and μ → 3e) on the basis of a single experimental facility is proposed. This approach makes it possible to improve the sensitivity level of relevant experiments by factors of 10⁵, 600, and 300 for, respectively, the first, the second, and the third of the above processes in relation to the existing experimental level. The approach is based on employing a pulsed proton beam and on combining a muon source and the detector part of the facility into a unified magnetic system featuring a nonuniform field. A new detector design involving separate units andmaking it possible to study all three muonic processes at a single facility that admits a simple rearrangement of the detectors used is discussed.     

Search for muon drift in copper

We report a preliminary test of whether muon diffusion in copper is limited by conventional conduction electron scattering or by nonadiabatic quantum damping as proposed by Kondo. Drift of the muon with electron wind when current is passed through a copper foil was not observed, indicating that electron scattering is not the dominant mechanism limiting muon diffusion. This result supports the Kondo theory.     

Angular correlation for nuclear muon capture

Formulae for the capture rates, gamma-neutrino correlations, and angular distributions of recoil in muon capture processes J_i J_f by an unpolarized nucleus for J_i ≦ 3 and J_f ≦ 5/2, with and without change of parity of nuclear levels, are given explicitely in terms of the multipole amplitudes. Relation of helicity amplitudes for muonic atom decay to the multipole amplitudes and to amplitudes introduced by other authors is presented. The derivation is based on kinematics only, and the formulae are strictly valid for the muon capture by any nuclei. The formulae are convenient for model calculations of partial transitions with realistic nuclear and muon wave functions and for the phenomenological analysis of a weak interaction.     

Radar studies using the “sura” facility

We review technical characteristics and applications of the VHF SURA radar based on the multipurpose research SURA facility of the Radiophysical Research Institute. Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 8, pp. 765–779, August 1999.     

The potential for neutrino physics at muon colliders and dedicated high current muon storage rings

Conceptual design studies are underway for muon colliders and other high-current muon storage rings that have the potential to become the first true “neutrino factories”. Muon decays in long straight sections of the storage rings would produce precisely characterized beams of electron and muon type neutrinos of unprecedented intensity. This article reviews the prospects for these facilities to greatly extend our capabilities for neutrino experiments, largely emphasizing the physics of neutrino interactions.     

Zero field spin relaxation studies as a probe of positive muon diffusion mechanisms

A theory of spin relaxation in zero external field is developed for a nonstationary distribution of diffusing particles. Application to μSR experiments in Nb and Bi is made to distinguish between models of muon diffusion in the presence of traps.