J. Spuller

The spatial resolution of the time projection chamber at triumf

Abstract The spatial resolution of the time projection chamber at TRIUMF has been investigated. The best resolution, σ ⋍ 200 μ m , occurs at the minimum drift length and for an optimum track to anode crossing angle determined by the magnetic field. The resolution worsens for tracks crossing at larger or smaller angles and for longer drift lengths. The observed resolution is quantitatively reproduced by considering the diffusion of the drifting electrons, the track to anode crossing angle, E × B effects near the anode wire and the discrete nature of the ionization process.

Gated grid system used with a time projection chamber

Abstract A gated grid system has been developed for the TRIUMF time projection chamber to suppress drift field distortions caused by positive produced at the endcap proportional wires. Good spatial resolution in the TPC has been thereby maintained over a large range of counting rates.

Search for muon‐electron and muon‐positron conversion

Limits on the lepton flavor violating reactions ..mu../sup -/+Z..-->..e/sup -/+Z and ..mu../sup -/+Z..-->..e/sup +/+(Z-2), muon-electron and muon-position conversion, have been obtained. Upper limits (90% C.L.) for the branching ratios compared to ordinary muon capture are: R/sub -/(Ti) = GAMMA(..mu../sup -/Ti..-->..e/sup -/Ti)/GAMMA(..mu../sup -/Ti capture) ..d/sup +/Ca*)/GAMMA(..mu../sup -/Ti capture)<1.7 x 10/sup -10/ and R/sub -/(Pb)<4.9 x 10/sup -10/.

Construction and Initial Tests of the Time Projection Chamber at TRIUMF

We have constructed an apparatus to search for the lepton number violating decay of the muon μ-Z → e-Z. The apparatus is based on the Time Projection Chamber principle. The main advantages are a large solid angle 60%, simple trigger, good energy resolution, particle identification and simplified electronics. The details of the apparatus are described and preliminary results are given.

An RF separator for cloud muons at triumf

A particle separator utilizing crossed magnetic and RF electric fields has been incorporated into the TRIUMF M9 secondary channel to produce a clean negative muon beam at 77 MeV/c ±5%. The separator is driven at the main cyclotron frequency (23 MHz) and phase locked to the primary proton beam. The pion and electron contaminants in the beam are suppressed to <0.1% and <1%, respectively.

The time projection chamber at triumf

The time projection chamber at TRIUMF is being used to search for muon‐electron conversion. The best spatial resolution in the TPC, σ≂200 μm, occurs at the minimum drift length and for an optimum track‐to‐anode crossing angle determined by the magnetic field. The observed resolution is dependent on th diffusion of the drifting electrons, the track‐to‐anode crossing angle, E↘×B↘ effects near the anode wire and the discrete nature of the ionization process. Distortions due to positive ions leaking back into the drift volume from the anode wire region have been nearly eliminated by the use of a pulsed dual grid system.

Update on the TPC at triumf

Abstract Several improvements have recently been made to the TRIUMF TPC. These include the addition of a grid system, corrections to the electrostatic field cage and a sequential gate generator. Our experience with this new TPC will be discussed.

Search for muon electron conversion μ−+Ti → e−+Ti

Abstract A progress report on a search for the lepton flavor violating reaction μ − +Ti → e − +Ti is presented. No evidence for this process has yet been found leading to an upper limit −11 (90% confidence level) relative to ordinary muon capture.

The TRIUMF Time Projection Chamber Data Acquisition System

The Time Projection Chamber (TPC) at TRIUMF was developed for the search for muon-electron conversion, a lepton number violating process. This paper describes the data acquisition system in use for the last two years. Basic components of the system are a multi-crate CAMAC acquisition system, external memory, PDP 11/40 and VAX 11/780 coupled through DECNET. A discussion of the various software packages for data-taking and on-line track reconstruction follows.

An RF Separator for Cloud Muons at TRIUMF

A particle separator utilizing a magnetic field crossed with an rf electric field has been built and incorporated into the M9 secondary channel to produce a clean negative muon beam at 77 MeV/c ± 5%. The separator is driven at the main cyclotron frequency (23 MHz) and phase locked to the primary proton beam. Separation is achieved by using both the temporal and velocity differences between the muons, produced near the production target (cloud muons), and both the pion and electron contaminants in the beam.