Further studies on a DTBX prototype for the CMS muon detector at LHC

The performance of a small prototype chamber of the baseline project for the muon barrel detector for CMS has been studied in a muon beam. Its efficiency with different gases and wire diameters, the trigger possibilities and the response in presence of a large number of electromagnetic secondaries associated to the muon are evaluated. The results are compared with a full Monte Carlo simulation.     

Status of the BNL muon (g-2) experiment

The muon (g-2) experiment at Brookhaven completed a first run in June and July 1997. The main components of the experiment, which include the superconducting inflector, the superferric storage ring, the electrostatic quadrupoles and the lead-scintillating fiber electron calorimeters, have been commissioned satisfactorily. Our first measurement of the ratio R of the spin precession frequency of the positive muon relative to that of a free proton, R=(3.707219±0.000048)×10^-3, is in good agreement with the previous CERN measurements for μ⁺ and μ^- , and has approximately the same uncertainty as each of these measurements. In spring 1998 a muon kicker was installed and successfully tested in the storage ring magnet and a significant improvement in the knowledge of the muon g-factor is expected from upcoming runs in August 1998 and January 1999     

The CDF forward muon system

The general properties of the toroids, drift chambers and trigger counters in the CDF forward muon (FMU) system are discussed. The operation of the PSL time-to-digital converter and the UW HOPU (Half Octant Pattern Unit) module is also described. The forward muon level 1 trigger is presented.     

Performance of the prototype chambers for the L3 muon filter

Several prototypes of brass tube chambers for the L3 muon filter have been built. Results are presented on tests with cosmic rays and muon beams.     

Muons probe strong hydrogen interactions with defective graphene

Here, we present the first muon spectroscopy investigation of graphene, focused on chemically produced, gram-scale samples, appropriate to the large muon penetration depth. We have observed an evident muon spin precession, usually the fingerprint of magnetic order, but here demonstrated to originate from muon-hydrogen nuclear dipolar interactions. This is attributed to the formation of CHMu (analogous to CH(2)) groups, stable up to 1250 K where the signal still persists. The relatively large signal amplitude demonstrates an extraordinary hydrogen capture cross section of CH units. These results also rule out the formation of ferromagnetic or antiferromagnetic order in chemically synthesized graphene samples.     

Theoretical studies of processes involving implanted muons

Recent advances in the theoretical study of implanted muons in solids include progress in quantitative modelling of the energetics of binding sites taken up by the muon after implantation. In the last two years, the range of materials that has been studied has grown from simple elemental crystals to complex molecular materials; path-integral methods have also been introduced to study the quantum-mechanical effects arising from the light mass of the muon.     

A new multidetector system with magnetic spectrograph for study of cosmic ray extensive air shower components

An array of detectors for simultaneous observation of different components of cosmic ray extensive air showers (EAS) is described. The detector array, comprising plastic scintillation counters as electron detectors, magnetic spectrograph units and a muon flash tube chamber as muon detectors and a large volume multiplate cloud chamber as hadron detector has been set up and is now being operated at NBU campus. The array of detectors is sensitive to air showers initiated by cosmic primaries of energy in the range 10¹⁴–10¹⁵ eV.     

A method for estimating muon production and penetration through a shield

An approximate expression is derived that describes muon production by high-energy protons and the subsequent attenuation of the muons in a shield. It is shown that the muon flux at x ahead of an interaction by a proton of energy ? GeV and where pions have a path length of Δ m in which to decay, will be given by:

$\text{φ=8.5×10}{}^{\mathrm{?2}}\text{εΔ}\text{x}{}^2\text{e}{}^{\mathrm{<mtext>?(</mtext><mtext>\alpha t</mtext><mtext>\epsilon </mtext><mtext>)</mtext>}}\text{μ/}\text{m}{}^2$

, where t is the shield thickness in m and α is an effective muon energy loss rate which has a value of 22 GeV/m for iron and 7.8 GeV/m for concrete. It is further shown that the effective muon attenuation mean-free path is equivalent to $\text{1}\text{16}$ of the range of a muon with the energy of the interacting proton.The width of the muon beam that passes through the shield is also considered and it is shown that the beam profile approximates a Gaussian distribution with a diameter at half-maximum intensity of:

$\text{d=}\text{4.6x}\text{εαt}\text{m}$

.Calculated muon fluxes are shown to correspond reasonably with those obtained by more sophisticated computer methods for proton energies up to at least 30 GeV and over the entire range of shield thicknesses of interest for radiation safety. Results of measurements of muon levels behind beam dumps under various conditions are presented and are shown to be in reasonable agreement with predictions based on the above model.     

Upgraded muon detection system for UA1 based on limited streamer tubes

We describe the construction and performance of the improved muon detection system of the UA1 experiment. The new position detectors, that complement the original muon detection system based on large planar drift chambers, are limited-streamer chambers for a total surface of 800 m². The coordinate parallel to the wires is readout through the especially developed STAR electronics that integrates and digitizes the signal from the strips. The intrinsic spatial resolution, determined in a test beam, is 400 μm, that achieved so far in the real system is 1.2 mm. The efficiency is evaluated to be (94.9±0.6)%.     

Ion dynamics in plasma compensation scheme

In this paper the ability of a plasma to compensate beam-induced fields at the interaction point of muon colliders is discussed. Among numerous factors that limit beam and plasma parameters for which a given compensation degree can be achieved, one of the most important limitations (the motion of plasma ions) is analyzed in details. It is found that this limitation is determined by an instability of the relative motion of plasma electrons and ions. It is shown that discussed parameters of ultimate muon colliders fall outside the applicability area of plasma compensation.     

Equivalent dose rate by muons to the human body

In this paper, the relative sensitivity from different human tissues of the human body, at a ground level, from muon cosmic radiation has been studied. The aim of this paper was to provide information on the equivalent dose rates received from atmospheric muons to human body, at the ground level. The calculated value of the effective dose rate by atmospheric muons plus the radiation levels of the natural annual background radiation dose, at the ground level, in the momentum interval of cosmic ray muon (0.2-120.0 GeV/c) is about 2.106±0.001 mSv/y, which is insignificant in comparison with the values of the doses from the top of the atmosphere.     

Muon Dynamics in the Multilayered Target H�CT/D2/H2�CD2 at Low Temperature

Recently, muon catalyzed fusion in the multilayered targets H/D/T at temperature 3 K has been investigated. The latest theoretical and experimental works have confirmed that muon conversion efficiency in such multilayered systems is low. This strongly affects the muon cycling coefficient in the structure H?CT/D₂/H₂?CD₂. The first layer emits t??(1s) atoms. They are moderated in the pure deuterium layer. In the third layer, the muonic deuterium atoms rapidly cascade and reach the ground state. The probability that a ??p atom reaches the 1s state depends on deuterium concentration. In low concentration of deuterium, the hyperfine transition of d??(1s) atom is of particular interest. A kinetic model for such processes is given. Our work clearly shows Wolfenstein?CGerstein (W.G.) effect.     

Hadron showers in iron and muon identification

We report on measurements of the punchthrough probability of high energy hadrons as a function of iron depth and hadron energy. These measurements were made in the Fermilab Meson Bottom test beam. The hadron momentum range was from 12 to 200 GeV/c and the maximum iron depth explored was 250 cm. Hadron shower characteristics as a function of iron depth and hadron energy are shown and compared with other data. Characteristics of a proportional tube detector and the use of such a detector in a muon identification system are described. The muon identification efficiency is studied for several configurations. Each configuration differs in the thickness of the steel absorbers and their locations among chambers.     

Contributions of muon spin rotation/relaxation/resonance to the understanding of problems in magnetism — Current and future

During these 25 years following the start of muon spin rotation/relaxation/resonance (μSR) studies on condensed matter, various new aspects of magnetic materials have been explored by using high sensitivity to the microscopic dynamical behaviour of the host magnetism, specifically, the studies on magnetic ordering in strongly-correlated electron systems, elementary excitations in conducting polymers and protein, etc. Intense (more than 10⁶/cm·s) and ultra-slow (below keV) muon beams to be available at future accelerator facilities may open new areas such as spin dynamics studies of surface magnetism, cluster particles, etc.     

Commissioning of the Rutherford Appleton Laboratory pulsed muon facility

The pulsed muon channel of the ISIS facility at the Rutherford Appleton Laboratory has been successfully commissioned as a tool for μSR research using polarised surface muons and for experiments requiring negative cloud muons. The beam line is described and the present performance given. At the present time, the pulsed muon beam gives 10⁵ μ⁺/s (2000 μ⁺/pulse) with very thin production targets (2.5 mm thick carbon) and 30% of the ISIS design proton current. μSR test spectra demonstrate the capability of the source and instrumentation, the performance relative to the continuous sources at the meson factories, and the potential for new science.     

Large drift chambers for future detectors

The design and construction of simple and stable drift chambers, suited for production in large quantities and sizes, is presented. These chambers are under construction for the muon detector of the L3 experiment at LEP.     

A mobile detector for measurements of the atmospheric muon flux in underground sites

Muons comprise an important contribution of the natural radiation dose in air (approx. 30 nSv/h of a total dose rate of 65-130 nSv/h), as well as in underground sites even when the flux and relative contribution are significantly reduced. The flux of muons observed underground can be used as an estimator for the depth in mwe (meter water equivalent) of the underground site. The water equivalent depth is important information to devise physics experiments feasible for a specific site. A mobile detector for performing measurements of the muon flux was developed in IFIN-HH, Bucharest. Consisting of two scintillator plates (approx. 0.9 m²) which measure in coincidence, the detector is installed on a van which facilitates measurements at different locations at the surface or underground. The detector was used to determine muon fluxes at different sites in Romania. In particular, data were taken and the values of meter water equivalents were assessed for several locations at the salt mine in Slanic-Prahova, Romania. The measurements have been performed in two different galleries of the Slanic mine at different depths. In order to test the stability of the method, also measurements of the muon flux at the surface at different elevations were performed. The results were compared with predictions of Monte-Carlo simulations using the CORSIKA and MUSIC codes.     

Method for Estimating the Instrumental Function of the Uragan Muon Hodoscope Based on Monte-Carlo Simulations

Measurement Techniques - We propose a method for determining the instrumental function of the URAGAN muon hodoscope based on the mathematical technique of Monte-Carlo simulation. Various components...     

Neutron multiplicity distribution for the muon catalyzed fusion reactions

A rigorous expression for the neutron multiplicity distribution in the muon catalyzed fusion reaction is obtained. Some problems of its use in the experimental data analysis are considered.     

Construction and test of the final CMS Barrel Drift Tube Muon Chamber prototype

A prototype of the CMS Barrel Muon Detector incorporating all the features of the final chambers was built using the mass production assembly procedures and tools. The performance of this prototype was studied in a muon test beam at CERN and the results obtained are presented in this paper.