117 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Spear"

open access

Lead-Glass Wall addition to the Spear Mark I Magnetic Detector

A ''Lead-Glass Wall,'' consisting of 318 lead-glass Cherenkov shower counters and three wire spark chambers, has been added to one octant of the SPEAR Mark I Magnetic Detector. The wall covers a solid angle of approximately 6 percent of 4..pi.. steradians and has been used to identify and measure the energies of electrons and photons produced in electron-positron collisions. The design, calibration, gain-monitoring, and performance of the system are described.

Date: October 1, 1977

Creator: Feller, J. M.; Barbaro-Galtieri, A. & Dorfan, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Selected results from the Mark II at SPEAR

Recent results on radiative transitions from the psi(3095), charmed meson decay, and the Cabibbo-suppressed decay tau ..-->.. K* ..nu../sub tau/ are reviewed. The results come primarily from the Mark II experiment at SPEAR, but preliminary results from the Crystal Ball experiment on psi radiative transitions are also discussed.

Date: June 1, 1980

Creator: Scharre, D.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Panel discussion on laboratory accelerator programs: present and future

The present SLAC accelerator program is summarized briefly, and the future of electron-positron colliders is discussed. Present activities discussed include the PEP storage ring, the SPEAR storage ring, the Linear Accelerator, and the SLAC Linear Collider (SLC) project. Future prospects include a larger scale linear collider. The stability requirements on acceleration are briefly discussed. (LEW)

Date: September 1, 1986

Creator: Richter, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mark III results from SPEAR

First results from the MARK III detector at SPEAR are presented based on 2.7 million J/psi decays. The eta/sub c/ is observed in three modes, J/psi ..-->.. ..gamma..eta/sub c/, (eta/sub c/ ..-->.. rho anti rho, eta..pi../sup +/..pi../sup -/, and phi phi). Using the phi phi mode, the eta/sub c/ spin-parity is determined to be 0/sup -/. The known radiative J/psi decays J/psi ..-->.. ..gamma..f(f ..-->.. ..pi../sup +/..pi../sup -/), ..gamma..eta'(eta' ..-->.. ..gamma..rho/sup 0/, eta..pi../sup +/.… more

Date: November 1, 1983

Creator: Toki, W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Beam-beam effect and luminosity in SPEAR

Measurements performed at SPEAR have been discussed and scaling laws for the maximum luminosity and the maximum linear tune shift parameter with energy are shown. There are two distinct regimes, one below 2 GeV where the linear tune shift parameter scales like xi/sub y/ approx. E/sup 2/ /sup 4/ and the other regime where this parameter is constant xi/sub y/ approx. = 0.05 to 0.06. In the lower energy regime the limit is reached when the vertical beam size is blown up to the acceptance of the st… more

Date: July 1, 1980

Creator: Wiedemann, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Models and simulations

On-line mathematical models have been used successfully for computer controlled operation of SPEAR and PEP. The same model control concept is being implemented for the operation of the LINAC and for the Damping Ring, which will be part of the Stanford Linear Collider (SLC). The purpose of this paper is to describe the general relationships between models, simulations and the control system for any machine at SLAC. The work we have done on the development of the empirical model for the Damping R… more

Date: September 1, 1983

Creator: Lee, M. J.; Sheppard, J. C.; Sullenberger, M. & Woodley, M. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Recent results from Mark II at SPEAR and PEP

Three results are presented: (1) The semi-leptonic branching ratio of the ..lambda../sub c/ has been measured at SPEAR to be B(..lambda../sub c//sup +/ ..-->.. e/sup +/X) = (4.5 +- 1.7)%. (2) Properties of tau-pair production have been measured at PEP at square root S = 29 GeV: sigma/sup tau tau//sigma/sup QED/ = 0.97 +- 0.05 +- 0.06; the forward-backward asymmetry is A/sub tau tau/ = (-3.5 +- 5.0)%; inclusive branching ratios are B(tau ..-->.. 1 Prong) = (86 +- 4)%, B(tau ..-->.. 3 Prongs) = (… more

Date: April 1, 1982

Creator: Strait, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dispersion function and closed orbit distortion in accelerator rings

Dispersion Function Distortion (DFD) affects accelerator operation and thus deserves attention, somehow as Closed Orbit Distortion (COD) does. Consequently, DFD correction schemes under computer control have been successfully developed and adopted in many rings such as PEP. It was realized during the author's study on the problem, however, that the existing DFD correction schemes ignore those terms that arise from bending magnets and their edges. Being of first order of correcting strength, the… more

Date: February 1, 1984

Creator: Liu, R.Z.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Hunt for the 1/sup 1/P/sub 1/ bound state of charmonium

Using the Crystal Ball detector at SPEAR, we have looked for evidence of the isospin-violating decay psi' ..-->.. ..pi../sup 01/P/sub 1/, where /sup 1/P/sub 1/ is the predicted spin-singlet p-wave bound state of charmonium. For a /sup 1/P/sub 1/ state at the predicted mass (approx. 3520 MeV), we obtain the 95% confidence level limits: BR(psi' ..-->.. ..pi../sup 01/P/sub 1/) < 0.55%, BR(psi' ..-->.. ..pi../sup 01/P/sub 1/)BR(/sup 1/P/sub 1/ ..-->.. ..gamma..n/sub c/ < 0.14%. These limits are com… more

Date: February 1, 1982

Creator: Porter, Frank C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Progress report on future accelerators

SLAC intends to pursue high energy physics work in the future along three lines: (1) continued exploration of electron and photon physics on stationary targets; (2) colliding beam physics using electron-positron storage rings; (3) single-pass collider physics with electrons using first the Stanford Linear Collider (SLC) and eventually a single-pass collider operating near the highest practical upper limit for such devices. These long-range plans are discussed.

Date: February 1, 1984

Creator: Panofsky, W.K.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

SLAC electron-positron colliders: present and future

Stanford University's colliding beam program is outlined, including the SPEAR and PEP colliders and the SLAC linear collider. The accelerator developments to be pursued on these facilities are discussed, as well as advanced accelerator research and development. The items covered in the advanced accelerator research include beamstrahlung, stability requirements, breakdown limits, and power sources. (LEW)

Date: September 1, 1986

Creator: Richter, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Recent results in e/sup +/e/sup -/ annihilation from SLAC

Recent results from the Mark II and Crystal Ball experiments at SLAC are presented. Mark II results include measurement of direct photon production at the psi and observation of charmed baryon production. The Crystal Ball experiment sees evidence for a new state at 2.98 GeV produced in a radiative transition from the psi'.

Date: November 1, 1979

Creator: Scharre, D.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Beam-blowup study for a weak-strong case

A comparison is made of experimental results obtained on two SLAC storage rings PEP and SPEAR with the theoretical calculations and the dependence of the phenomenon on different machine parameters is studied. In the present paper we present such a comparison with reasonably good agreement between the experiment and the theory. The important conclusion from our study is that any valid theory of the beam-beam phenomenon should take into account the asymmetries of the machine parameters arising in… more

Date: July 1, 1983

Creator: Kheifets, S.; Helm, R. & Shoaee, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Polarization of a stored electron beam

Synchrotron radiation by a point charge is a familiar subject in classical electrodynamics. Perhaps less familiar are some quantum mechanical corrections to the classical results. Some of those quantum aspects of synchrotron radiation are described. One of the quantum effects leads to the expectation that electrons in a storage ring will polarize themselves to 92% - a surprisingly high value. A semi-classical derivation of the quantum effects is given. An effort has been made to minimize the ne… more

Date: July 1, 1981

Creator: Chao, A.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hadron production by e/sup +/e/sup -/ annihilation at center-of-mass energies between 2. 6 and 7. 8 GeV

Results are presented on multihadron production by e/sup +/e/sup -/ annihilation from the Mark I and Mark II detectors at SPEAR. Other than the narrow resonances psi (3095) and psi' (3684), the total hadronic cross section varies between 36.5 and 6.4 nb over the center-of-mass energy range 2.6 to 7.8 GeV with complicated structure near 4.1 GeV not completely resolved by these measurements. Evidence for scaling of inclusive momentum distributions of hadrons is presented.

Date: October 1, 1979

Creator: Siegrist, J.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Commissioning and Operation of the Nuclear Physics Injector at SLAC

The new Nuclear Physics Injector (NPI) approved for construction in October of 1983 was completed by September of 1984, and delivered short pulse beams for SPEAR ring checkout in mid-October. Long pulse beams of up to 1.6 microsecond length were also demonstrated. The paper describes the startup operation, reviews the performance characteristics, and discusses the beam transport optics used to deliver 1 to 4 GeV beams to nuclear physics experiments in End Station A.

Date: March 1, 1985

Creator: Koontz, R. F.; Miller, R. H.; Leger, G. K. & Iverson, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Recent results for Mark III

This paper presents recent results from the Mark III detector at SPEAR, in the open charm sector. The first topic discussed is the reanalysis of the direct measurement of the D hadronic branching fractions, where a detailed study has been made of the Cabibbo suppressed and multi-..pi../sup 0/'s D decays backgrounds in the double tag sample. Next, the Dalitz plot analysis of the D decays to K..pi pi.. is presented, leading to the relative fractions of three-body versus pseudoscalarvector decays.… more

Date: December 1, 1987

Creator: Brient, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Recent results from the Mark II detector at SPEAR

Recent results rom the Mark II Detector at SPEAR are presented. These include measurements of the decays tau/sup -/ ..-->.. rho/sup -/..nu../sub tau/ and tau/sup -/ ..-->.. K*/sup -/(890)..nu../sub tau/, observation of direct photons at the psi, inclusive proton and ..lambda.. production and measurements of charmed baryon and charmed meson decays.

Date: November 1, 1979

Creator: Dorfan, Jonathan

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

GIANT: a computer code for General Interactive ANalysis of Trajectories

Many model-driven diagnostic and correction procedures have been developed at SLAC for the on-line computer controlled operation of SPEAR, PEP, the LINAC, and the Electron Damping Ring. In order to facilitate future applications and enhancements, these procedures are being collected into a single program, GIANT. The program allows interactive diagnosis as well as performance optimization of any beam transport line or circular machine. The test systems for GIANT are those of the SLC project. The… more

Date: April 1, 1985

Creator: Jaeger, J.; Lee, M.; Servranckx, R. & Shoaee, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Review of e/sup +/e/sup -/ reactions in the energy range 3 to 9 GeV

The current experimental status of the tau and charmed particles in medium-energy e/sup +/e/sup -/ annihilations is reviewed.

Date: October 1, 1979

Creator: Kirkby, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Topics in the Physics of Particle Accelerators

High energy physics, perhaps more than any other branch of science, is driven by technology. It is not the development of theory, or consideration of what measurements to make, which are the driving elements in our science. Rather it is the development of new technology which is the pacing item. Thus it is the development of new techniques, new computers, and new materials which allows one to develop new detectors and new particle-handling devices. It is the latter, the accelerators, which are … more

Date: July 1, 1984

Creator: Sessler, Andrew M.

Item Type: Book

Partner: UNT Libraries Government Documents Department

open access

STRONG TURBULENCE and THE ANOMALOUS LENGTH OF STORED PARTICLE BEAMS

A dispersion relation, including strong turbulence, is derived for short-wavelength longitudinal self-perturbations of bunched electron beams. The effects of radiation damping and quantum excitation are included. Assuming that turbulence stabilizes coherent oscillations allows the derivation of a formula for bunch length which gives excellent fits to the data from SPEAR. As a special case of the formalism, an integral equation which describes the longitudinal self-perturbations of proton beams … more

Date: November 1, 1975

Creator: Channell, Paul J. & Sessler, Andrew M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

New wiggler beam line for SSRL

A new high-intensity-beam line with a wiggler magnet source is described. This project, in final stages of design, is a joint effort between Lawrence Berkeley Laboratory (LBL), the Exxon Research and Engineering Company (EXXON), and the Stanford Synchrotron Radiation Laboratory (SSRL). Installation at SSRL will begin in the summer of 1982. The goal of this project is to provide extremely high-brightness synchrotron radiation beams over a broad spectral range from 50 eV to 40 keV. The radiation … more

Date: August 1, 1982

Creator: Hoyer, E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Initial operation of SSRL wiggler in spear

A 3 lambda planar, magnetic wiggler has been designed, built, installed and operated in the SPEAR storage ring. Its primary purpose is to provide tunable synchrotron radiation (SR) with a higher energy and intensity than previously available for a new SR beam line just commissioned at the Stanford Synchrotron Radiation Laboratory. Because the magnet operates from 0-18 kG, it should also produce undulator radiation (UR). Since the wiggler influences storage ring operation in both single beam and… more

Date: March 1, 1979

Creator: Berndt, M.; Brunk, W.; Cronin, R.; Jensen, D.; Johnson, R.; King, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department