Showing papers by "TRIUMF published in 1985"
TL;DR: In this paper, the effect of charged particle radiation on the magnetic behavior of rare earth cobalt (REC) permanent magnet materials was studied in a high radiation environment and the results of exposing samples of samarium-cobalt and other permanent magnet material to a beam of protons were described.
Abstract: At TRIUMF the use of samarium-cobalt permanent magnet quadrupoles as the first element in a secondary channel has been studied as a means of increasing the solid angle acceptance of the channel. The high remanent induction Br and high coercive force Hc of rareearth cobalt (REC) can be utilized to produce a high-gradient quadrupole field in an extremely compact magnet. Although many properties of REC material have been measured, little is known about the effect of charged particle radiation on the magnetic behaviour. As the TRIUMF application requires the magnets to operate in a high radiation environment it was considered essential to study this effect. This paper describes the results of exposing samples of samarium-cobalt and other permanent magnet materials to a beam of protons.
55 citations
TL;DR: The cloudy bag model is extended to incorporate chiral SU( 3) & SU(3) symmetry, in order to describe 5-wave KX and KX scattering, and strongly supports the contention that the A*(1405) is a FYX bound state.
Abstract: The cloudy bag model (CBM) is extended to incorporate chiral SU(3) & SU(3) symmetry, in order to describe 5-wave KX and KX scattering. In spite of the large mass of the kaon, the model yields reasonable results once the physical masses of the mesons are used. We use that version of the CBM in which the mesons couple to the quarks with an axial-vector coupling throughout the bag volume. This version also has a meson-quark contact interaction with the same spin-flavor structure as the exchange of the octet of vector mesons. The present model strongly supports the contention that the A*(1405) is a FYX bound state.
50 citations
TL;DR: A model-dependent fit of the K X-ray spectrum gives a Kα energy of 8.9± 0.3 keV, corresponding to a strong interaction shift of (−0.5±0.3) keV.
39 citations
TL;DR: In this paper, the ππ and π-meson exchange three-body force (TBF) is extended to include ϱ- and ε-mesons exchange and a qualitative discussion is given of the origin of the potentials which are constrained by the low energy theorems of Thirring, Beg, and Kroll and Ruderman and supplemented by Δ-isobar contributions.
37 citations
TL;DR: In this paper, a search was performed for the lepton-flavor-nonconserving reaction using a time-projection chamber and no candidate events were observed, resulting in a limit of \ensuremath{\Gamma}(${m,n,m,m}$+Ti\ensurem{n}capture) 1.6\ifmmode\times\else\texttimes\fi{}
Abstract: A search has been performed for the lepton-flavor-nonconserving reaction ${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$+Ti\ensuremath{\rightarrow}${e}^{\mathrm{\ensuremath{-}}}$+Ti using a time-projection chamber. No candidate events were observed, resulting in a limit of \ensuremath{\Gamma}(${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$+Ti\ensuremath{\rightarrow}${e}^{\mathrm{\ensuremath{-}}}$+Ti) / \ensuremath{\Gamma}(${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$+Ti\ensuremath{\rightarrow}capture) 1.6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ (90% C.L.) for this reaction relative to ordinary muon capture.
29 citations
TL;DR: The tensor polarization in elastic scattering has been measured as a function of energy and the data do not lend support to the existence of dibaryon resonance effects at these kinematic ranges.
Abstract: The tensor polarization ${t}_{20}$ in ${\ensuremath{\pi}}^{+}d$ elastic scattering has been measured as a function of energy at 15\ifmmode^\circ\else\textdegree\fi{} (laboratory) over the energy range ${T}_{\ensuremath{\pi}}=118 \mathrm{to} 148$ MeV. The angular distributions at 135 and 142 MeV between 15\ifmmode^\circ\else\textdegree\fi{} and 35\ifmmode^\circ\else\textdegree\fi{} were also measured. The ${t}_{20}$ values are negative for all energies and angles investigated and are consistent with the data of Holt et al. and Ungricht et al., resolving the previous discrepancy with the results of Ulbricht et al., Gr\"uebler et al., and Konig et al. As there are no significant rapid variations in ${t}_{20}$, our data do not lend support to the existence of dibaryon resonance effects at these kinematic ranges.
27 citations
TL;DR: In this article, a relativistic form of the Brueckner theory of nuclear matter is applied to an extended meson-exchange model for the NN-interaction which contains explicit 2π-and πϱ-exchanges.
24 citations
15 Oct 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a 3 m long Wien filter or dc separator was used to rotate the muon spin from its natural orientation, antiparallel to the beam momentum, by 90° into a transverse orientation.
Abstract: The TRIUMF low energy muon channel, M20, was completely rebuilt in 1983. Amongst the features incorporated into the new channel is a 3 m long Wien filter or dc separator. For surface and sub-surface μ + beams, the magnetic field of this device is sufficient to rotate the muon spin from its natural orientation, antiparallel to the beam momentum, by 90° into a transverse orientation. The performance of this muon “spin rotator” is described.
24 citations
TL;DR: In this article, the weak interaction form factors of the octet baryons were calculated using the cloudy bag model and the center-of-mass correction of the center of mass correction was discussed.
23 citations
TL;DR: In this article, the potential parameters for the real vector and scalar components of the Dirac optical model were investigated and two types of parameter sets were found: shallow and deep potentials.
21 citations
TL;DR: In this article, cross-section and analyzing-power measurements were performed for the 9 Be(p¯, p 0 ) 9 Be and 9 Be((p 2 ) 9 BE*) reactions.
TL;DR: In this paper, a new description of hadronic bound states consisting of a single heavy quark and one or more light quarks (or antiquarks) was proposed, where heavy quarks are treated as an infinitely massive, nonrelativistic object situated at the center of a spherical cavity.
Abstract: A new description of hadronic bound states consisting of a single heavy quark (or antiquark) and one or more light quarks (or antiquarks), in which the heavy quark is treated as an infinitely massive, nonrelativistic object situated at the center of a spherical cavity, is proposed. Because of the absence to a large extent of center-of-mass corrections, which are quite large in the traditional model, a cleaner phenomenological description of systems containing a heavy quark should result. As a preliminary application, the spectrum of charmed mesons and their strong and electromagnetic branching ratios are computed. Directions for future applications of this model are discussed.
TL;DR: The masses of high-spin mesons are calculated using a relativized quark model that predicts that the leading spin states lie on linear Regge trajectories.
Abstract: The masses of high-spin mesons are calculated using a relativized quark model. The model predicts that the leading spin states lie on linear Regge trajectories.
TL;DR: In this paper, narrow states observable through the emission of monoenergetic charged pions have been searched for in p p annihilation at rest in a gaseous hydrogen target where annihilation from atomic angular momentum L = 1 states dominates.
TL;DR: In this paper, the pionic 4f-3d and 5g-4f transitions were measured in 208 Pb and 209 Bi and the 3d widths obtained are in reasonable agreement with theory, and do not support the anomalously small values previously reported.
TL;DR: In this article, the spin-spin correlation parameters A LL, A NN, A SS, A SL and spin asymmetries A NO and A ON have been measured for the reaction p p → pn π + with incident beam energies of 510, 465 and 420 MeV.
15 Jan 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, 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, and good spatial resolution has been thereby maintained over a large range of counting rates.
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.
TL;DR: Gate arrays are used to implement designs which would require one hundred or more normal integrated circuits, thus greatly reducing the area of a FASTBUS printed circuit board needed for the interface.
Abstract: A design concept is presented for a set of semicustom integrated circuits which will interface a master or slave module to a FASTBUS segment. These devices will perform master arbitration, address recognition, handshaking, data pipe-lining and many other standard FASTBUS protocol tasks. Gate arrays are used to implement designs which would require one hundred or more normal integrated circuits, thus greatly reducing the area of a FASTBUS printed circuit board needed for the interface.
15 Jan 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the TRIUMF polarized neutron beam facility was upgraded for use in high precision neutron scattering experiments, which was used to determine charge symmetry breaking in n−p elastic scattering, to study neutron radiative capture by hydrogen, and a measurement of the spin correlation parameter Ann.
Abstract: The polarized neutron beam facility at TRIUMF has been upgraded for use in high precision neutron scattering experiments. Polarized neutrons are produced via transverse polarization transfer in the D(p,n)2p reaction at 9° in the lab. Proton beam position on the LD2 production target is stabilized to better than ±0.2 mm using a feedback system controlling beam line elements. The region of uniform neutron beam intensity at the experimental target location is a rectangular area 56 mm wide and 40 mm high. In that area the neutron beam intensity is 9 × 103 (100 nA cm2 s) and the neutron polarization is 50%. The facility is being used to determine charge symmetry breaking in n−p elastic scattering, to study neutron radiative capture by hydrogen, and a measurement of the spin correlation parameter Ann.
TL;DR: In this paper, the authors measured the muon spin relaxation functions in the magnetic superconductor Y9Co7 for T ≳ 2.0 K and at zero applied field, consistent with the high degree of inhomogeneity of the (not long-range) ordering and coexisting but non-competing magnetic and superconducting properties in the hybrid state.
15 Nov 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors measured the properties of a photomultiplier with proximity dynodes and 10 wire anodes, which allowed them to determine the position of emission of the photoelectrons from the cathode with an accuracy of 1.3 mm fwhm.
Abstract: We have measured the properties of a specially developed photomultiplier with proximity dynodes and 10 wire anodes. This design allows us to determine the position of emission of the photoelectrons from the cathode with an accuracy of 1.3 mm fwhm. This tube is also extremely fast due to the short transit time and the geometry of its dynodes.
15 Jan 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a detection device was developed to allow precision measurements of n−p elastic scattering of 150 to 500 MeV polarized neutron beams at TRIUMF with a precision of ± 0.001.
Abstract: Detection equipment has been developed to allow precision measurements of n−p elastic scattering of 150 to 500 MeV polarized neutron beams at TRIUMF. The apparatus permits a determination of the difference in angle, ‡θ, at which the neutron and proton analyzing powers An and Ap cross zero with a precision of ±0.04° lab at 500 MeV. From this difference in ‡θ the difference between An and Ap can be obtained to a precision of ±0.001.
TL;DR: Harmonic expansions on the internal compact coset manifold G/H for the (4+K)-dimensional Rarita-Schwinger fields are developed and the resulting four-dimensional effective Lagrangian describes an infinite tower of massive spin-(3/2) and spin-1/2 fields.
Abstract: Harmonic expansions on the internal compact coset manifold G/H for the (4+K)-dimensional Rarita-Schwinger fields are developed. The dimensional reduction of the Rarita-Schwinger Lagrangian coupled to gravity in 4+K dimensions is carried out using these expansions. The resulting four-dimensional effective Lagrangian describes an infinite tower of massive spin-(3/2) and spin-1/2 fields, coupled minimally and nonminimally to gauge fields. The masses of the Dirac fields are not given by the eigenvalues of the internal Rarita-Schwinger operator as is usually supposed.
TL;DR: In this article, a Test Facility with operating characteristics equivalent to the TRIUMF RF system was used to generate a flat-topped RF dee voltage at full operating values.
Abstract: A Test Facility with operating characteristics equivalent to the TRIUMF RF system was used to generate a flat-topped RF dee voltage at full operating values. The fundamental at 23 MHz, and the third harmonic at 69 MHz were combined in the single resonator. No difficulty was encountered with multipactoring in the addition of the third harmonic when the fundamental voltage was on at the level of a few kilovolts. Since the TRIUMF dees are flattened coaxial ?/4 lines with uniform dee-to-liner spacing, the natural frequencies f1 and f3 fall quite near a 3/1 ratio. Only a slight warping of the resonator in two locations that affect f1 and f3 differently is required to tune for a given f1 and for f3 = 3f1, precisely. With the two high power signals (1800 kW at 23 MHz and ~-100 kW at 69 MHz in TRIUMF; 45 kW and ~4 kW in the Test Facility) combined in one resonator, rather large filters in addition to the impedance matching networks are required in each drive line for isolation of the transmitters. The results of the tests and the physical layout will be described as well as the control systems for autotuning and for amplitude and phase of the two voltages.
TL;DR: In this article, a chain of 5 fast-cycling synchrotrons and dc storage rings is proposed to accelerate the proton beam from TRIUMF to 30 GeV.
Abstract: To accelerate the 100 ?A proton beam from TRIUMF to 30 GeV a chain of 5 fast-cycling synchrotrons and dc storage rings is proposed. 450 MeV H- ions from TRIUMF are injected by stripping into the Accumulator ring. A 50 Hz Booster synchrotron then accelerates the proton pulse to 3 GeV, where the frequency swing is almost complete. In the main tunnel (170 m radius) are the Collector ring, which collects 5 Booster pulse trains, the 10 Hz Driver synchrotron and the dc Extender ring, where beam is stored for slow resonant extraction. The rings use separated function lattices, designed for very high transition energy. Dual frequency magnet power supplies provide a 3:1 rise:fall ratio, reducing the peak rf voltage requirements to 600 kV for the Booster (46-61 MHz) and 2400 kV in the Driver (61-63 MHz). RF beam splitters will be used to program beam bunches between 4 proton lines and vary the pulse spacing from 16 ns to 64 ns.
TL;DR: In this article, the pionic fission 6 Li (π +, 3 He ) 3 He have been measured at pion energies of 60 and 80 MeV and the differential cross section is found to decrease monotonically with cos 2 θ ∗ and is compared with a theoretical prediction.
15 May 1985-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the authors reviewed the operational experience of the currently installed H− cyclotron systems in the US, Britain, Germany and Canada, and evaluated the performance of the presently installed machines.
Abstract: Over the past few years H− cyclotrons have been introduced as powerful radioisotope producers. Four of these machines, supplied by The Cyclotron Corporation of Berkeley, California, are now in regular operation in the US, Britain, Germany and Canada. They routinely accelerate protons, variable in energy from 11 to 42 MeV, at beam currents of up to 200 μA after extraction. Negative ion cyclotrons feature simplicity of extraction, ease of varying the energy and potential for more than one extracted beam. Target systems are installed in the external beams, thus eliminating much of the usual activation and contamination of the cyclotron. Operational experience with the presently installed machines is reviewed.
TL;DR: In this paper, the precessions for discrete γ-ray transitions in the reaction 24 Mg( 136 Xe,4n) 156 Dy at 600 and 620 MeV incident beam energy were measured.
01 Feb 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: 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 as discussed by the authors.
Abstract: 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.
TL;DR: A simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction, which reflects the opacity of a nucleus to a source of internal energetic protons.
Abstract: The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$xn) double charge exchange reactions on bismuth ${(}^{209}$Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of $^{211}\mathrm{At}$ activity in thin (\ensuremath{\sim}1 mg/${\mathrm{cm}}^{2}$), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed $^{211}\mathrm{At}$ activity although even at the highest energies, the contribution to products lighter than $^{207}\mathrm{At}$ was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product ${(}^{210}$At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about $^{204}\mathrm{At}$. The most probable momentum transfer deduced from these distributions for the initial ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of $^{210}\mathrm{Po}$ from a (p,${\ensuremath{\pi}}^{0}$) reaction on $^{209}\mathrm{Bi}$, but radically different from that observed for inclusive ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.