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Direct electron pair production in. pi. /sup -/p interactions at 16 GeV/c and a model for direct lepton and photon production at low P/sub T/

Description: The production of prompt electron-positron pairs in 16 GeV/c ..pi../sup -/p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contributions of direct and Dalitz decay of known resonances in the kinematic range defined by 0.1 less than or equal to x less than or equal to 0.45, 0 less than or equal to P/sub T/ less than or equal to 0.8 GeV/c and 0.2 less than or equal to M(e/sup +/e/sup -/) less than or equal to 0.7 GeV/c/sup 2/. The excess signal decreases slowly with increasing M, but exhibits very steep x and P/sub T//sup 2/ dependence. The contribution of this signal to the e/sup +/e/sup -//..pi../sup +/..pi../sup -/ and ..gamma../..pi.. ratios is discussed. Detailed comparisons are made between e/sup +/e/sup -/ distributions and the corresponding low mass ..mu../sup +/..mu../sup -/ distributions, and a simple production mechanism is proposed which describes the 16 GeV/c data well. The implications for direct photon production are presented, and it is shown that the model provides simultaneously a good description of the experimental data on the (e/..pi..) and (..mu../..pi..) ratios for p/sub T/ < 1 GeV/c.
Date: July 1, 1981
Creator: Blockus, D.; Dunwoodie, W. & Leith, D.W.G.S.
Partner: UNT Libraries Government Documents Department

Design of an electron beam spectral modification system

Description: We report the design of a spectral modification system (SMS) for use with the proposed NEAL linac-pulse stretcher ring, cw electron beam facility. The SMS allows tailoring of the energy distribution of electrons in beams produced by a pulsed linac operating in the transient beam loading (TBL) regime. Modification of the energy distribution of electrons injected into the pulse strecher ring will increase the duty factor of current extracted from the ring and improve the efficiency of the extraction process. Physically, the SMS consists of an anisochronous, achromatic magnetic lattice followed by a pair of traveling-wave accelerating sections. For beams in the energy range of 500 MeV to 4 GeV, TBL ripple on the energy envelope of microsecond long beam spills is expected to be reduced from 1% peak-peak to less than 0.01% while the desired width of the energy profile due to the phase extent of the microbunches in the beam spill is preserved.
Date: October 1, 1981
Creator: Sheppard, J.C.; York, R.C.; Norum, B.E. & McCarthy, J.S.
Partner: UNT Libraries Government Documents Department

Exclusive processes in quantum chromodynamics

Description: Large momentum transfer exclusive processes and the short distance structure of hadronic wave functions can be systematically analyzed within the context of perturbative QCD. Predictions for meson form factors, two-photon processes ..gamma gamma.. ..-->.. M anti M, hadronic decays of heavy quark systems, and a number of other related QCD phenomena are reviewed.
Date: June 1, 1981
Creator: Brodsky, S.J. & Lepage, G.P.
Partner: UNT Libraries Government Documents Department

Crystal Ball evidence for new states

Description: Evidence for three new particles observed in the Crystal Ball detector is presented. The first particle, at 3592 MeV, is seen inclusively in ..gamma.. transitions from psi', and is thus a candidate for eta/sub c/'. The other two, at 1440 and 1640 MeV, are best seen in exclusive decays of psi involving a prompt ..gamma.., and are thus candidates for bound states of two gluons. Detailed reasons are presented to support the contention that these states are distinct from previously observed candidates such as E(1420). Alternative hypotheses are discussed.
Date: September 1, 1981
Creator: Coyne, D.G.
Partner: UNT Libraries Government Documents Department

Initial-state interactions, factorization, and the Drell-Yan process

Description: It is shown that initial state interactions violate the factorization conjecture for the Drell-Yan process order by order in perturbation theory. Also, the effects of elastic and inelastic initial state interactions on the observed cross sections are discussed.
Date: December 1, 1981
Creator: Bodwin, G.T.; Brodsky, S.J. & Lepage, G.P.
Partner: UNT Libraries Government Documents Department

Baryon production at PEP

Description: Measurements of inclusive ..lambda.. + anti ..lambda.. production for 1.0 less than or equal to p less than or equal to 10.0 GeV/c and p + anti p production for 0.4 less than or equal to p less than or equal to 2.0 GeV/c show significant baryon production in e/sup +/e/sup -/ annihilation at E/sub cm/ = 29 GeV. ..lambda.. + anti ..lambda.. production represents 0.2 ..lambda..'s or anti ..lambda..'s per PEP event while the observed p + anti p production implies all baryon-antibaryon pair production is occurring at least as often as 0.6 per event, depending on the yet to be measured p + anti p production at high momentum. Comparisons are made with the first theoretical attempts to account for baryon production at these energies.
Date: September 1, 1981
Creator: Goldhaber, G. & Weiss, J.M.
Partner: UNT Libraries Government Documents Department

Beam parametr measurements for the SLAC linear collider

Description: A stable, closely-controlled, high-intensity, single-bunch beam will be required for the SLAC Linear Collider. The characteristics of short-pulse, low-intensity beams in the SLAC linac have been studied. A new, high-intensity thermionic gun, subharmonic buncher and S-band buncher/accelerator section were installed recently at SLAC. With these components, up to 10/sup 11/ electrons in a single S-band bunch are available for injection into the linac. the first 100-m accelerator sector has been modified to allow control of short-pulse beams by a model-driven computer program. Additional instrumentation, including a computerized energy analyzer and emittance monitor have been added at the end of the 100-m sector. The beam intensity, energy spectrum, emittance, charge distribution and the effect of wake fields in the first accelerator sector have been measured. The new source and beam control system are described and the most recent results of the beam parameter measurements are discussed.
Date: January 1, 1981
Creator: Clendenin, J.E.; Blocker, C. & Breidenbach, M.
Partner: UNT Libraries Government Documents Department

Fundamental tests and measures of the structure of matter at short distances

Description: Recent progress in gauge field theories has led to a new perspective on the structure of matter and basic interactions at short distances. It is clear that at very high energies quantum electrodynamics, together with the weak and strong interactions, are part of a unified theory with new fundamental constants, new symmetries, and new conservation laws. A non-technical introduction to these topics is given, with emphasis on fundamental tests and measurements. 21 references.
Date: July 1, 1981
Creator: Brodsky, S.J.
Partner: UNT Libraries Government Documents Department

Exclusive final states from photon-photon collisions at SPEAR

Description: Studies of exclusive final states produced by the two-photon process have been made at SPEAR by the Mark II and by the Crystal Ball Collaborations. Measurements of ..pi../sup +/..pi../sup -/ and ..pi../sup 0/..pi../sup 0/ production in the mass region 500 MeV/c/sup 2/ < m/sub ..pi pi../ < 2000 MeV/c/sup 2/ are presented. These data include strong signals from the well-known f(1270) meson. The A/sub 2/(1310) has been observed via its ..pi../sup 0/ eta decay mode and its partial width to ..gamma gamma.. has been determined. A measurement of the cross section for the reaction ..gamma gamma.. ..-->.. ..pi../sup +/..pi../sup -/..pi../sup +/..pi../sup -/ is reported. This channel is found to be small just above the four pion threshold, but exhibits a large enhancement near the rho/sup 0/rho/sup 0/ threshold.
Date: May 1, 1981
Creator: Burke, D.L.
Partner: UNT Libraries Government Documents Department

Exceptional groups and elementary-particle structures

Description: A new finite-dimensional quantum mechanical space is constructed over the complex octonionic plane using the recently developed algebraic techniques of Jordan pairs and inner ideals. The automorphism group of this structure is E/sub 6/ x U(1), realized on precisely two E/sub 6/ irreps which is abstracted as a (topless) model for grand unification.
Date: September 1, 1981
Creator: Biedenharn, L.C. & Truini, P.
Partner: UNT Libraries Government Documents Department

CID thermionic gun system

Description: A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10/sup 11/ electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented.
Date: October 1, 1981
Creator: Koontz, R.F.
Partner: UNT Libraries Government Documents Department

Coordinate measurement by current division: a simple system for multichannel detectors

Description: A simple current-division scheme is described based on an unorthodox connection of the 733 amplifier chip: a common-base input can be obtained by grounding the normal inputs and driving a gain control terminal. With ganged multiwire chambers detecting cosmic rays in the proportional region, under realistic operating conditions (charge approx. 2 picocoulombs per gap), the resolution is about 2% of full length. Calibration procedures are discussed, as are the effects of changing various parameters.
Date: August 1, 1981
Creator: Gottschalk, B.
Partner: UNT Libraries Government Documents Department

Linear collider: a preview

Description: Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.
Date: November 1, 1981
Creator: Wiedemann, H.
Partner: UNT Libraries Government Documents Department

Measurements of the decays tau/sup -/. -->. rho/sup -/. nu. /sub tau/, tau/sup -/. -->. pi. /sup -/. nu. /sub tau/ and tau/sup -/. -->. K*-(892). nu. /sub tau/ using the MARK II detector at SPEAR

Description: Measurements of the branching fractions for the Cabibbo favored decays tau/sup -/ ..-->.. rho/sup -/ ..-->.. ..pi../sup -/..nu../sub tau/ and the Cabibbo suppressed decay mode tau/sup -/ ..-->.. K*/sup -/ (892)..nu../sub tau/ are presented. The energy dependence of the tau/sup +/tau/sup -/ production cross section is obtained for the decays tau/sup -/ ..-->.. rho/sup -/..nu../sub tau/ and these spectra agree well with the classification of the tau/sup -/ as a spin-1/2 point particle. Fits to the production cross section yield a measurement of M/sub tau/ = (1787 +- 10) MeV/c/sup 2/ for the tau mass. Ninety-five percent confidence upper limits for the forbidden decay tau/sup -/ ..-->.. K*/sup -/(1430)..nu../sub tau/ and the tau neutrino mass are presented.
Date: April 1, 1981
Creator: Dorfan, J.
Partner: UNT Libraries Government Documents Department

Theory of hadronic production of heavy quarks

Description: Conventional theoretical predictions for hadronic production of heavy quarks (Q anti Q) are reviewed and confronted with data. Perturbative hard scattering predictions agree qualitatively well with hidden Q anti Q production (e.g., psi, chi, T) whereas for open Q anti Q-production (e.g., pp ..-->.. ..lambda../sub c//sup +/X) additional mechanisms or inputs are needed to explain the forwardly produced ..lambda../sub c//sup +/ at ISR. It is suggested that the presence of c anti c-pairs on the 1 to 2% level in the hadron Fock state decomposition (intrinsic charm) gives a natural description of the ISR data. The theoretical foundations of the intrinsic charm hypotheses together with its consequences for lepton-induced reactions is discussed in some detail.
Date: July 1, 1981
Creator: Peterson, C.
Partner: UNT Libraries Government Documents Department

SPEAR results, 1981

Description: New results from SPEAR on the inclusive photon spectrum at the psi' and on J/psi radiative transitions are presented. Evidence for an eta/sub c/' candidate is observed in the psi' inclusive photon spectrum at a mass M = 3592 +- 5 MeV. A new resonance, the theta(1640) which is observed to decay into eta eta, has been seen in radiative transitions from the J/psi. The spin-parity of the l(1440), previously observed in J/psi radiative transitions and originally identified as the E(1420), has been determined to be 0/sup -/.
Date: September 1, 1981
Creator: Scharre, D.L.
Partner: UNT Libraries Government Documents Department

Status of heavy-lepton searches

Description: Searches for heavy leptons using e{sup +}e{sup -} annihilation, lepton-hadron collisions, photon-hadron collisions, hadron-hadron collisions, and studies of macroscopic matter are reviewed. The present experimental status and future possibilities are summarized.
Date: June 1, 1981
Creator: Perl, M.L.
Partner: UNT Libraries Government Documents Department

Two-photon physics as a probe of hadron dynamics

Description: Two-photon collisions provide an ideal laboratory for testing many features of quantum chromodynamics, especially the interplay between the vector-meson-dominated and point-like hadronic interactions of the photon. A number of QCD applications are discussed, including: jet and single-particle production at large transverse momentum; the photon structure function and its relationship to the ..gamma.. ..-->.. q anti q wave function; and the possible role of gluonium states in the ..gamma gamma.. ..-->.. rho/sup 0/rho/sup 0/ channel. Evidence that even low momentum transfer photon-hadron interactions are sensitive to the point-like ..gamma.. ..-->.. q anti q coupling is discussed.
Date: May 1, 1981
Creator: Brodsky, S.J.
Partner: UNT Libraries Government Documents Department

Study of the emission performance of high-power klystrons: SLAC XK-5

Description: There are hundreds of high power klystrons operated in the Linac gallery and about fifty to sixty tubes fail every year. The lifetime ranges from a few thousand up to seventy thousand hours except those which fail during an early period. The overall percentage of failures due to emission problems is approximately 25%. It is also noted that a 10% increase in mean lifetime of klystrons will reduce the overall cost per hour as much as a 10% increase in efficiency. Therefore, it is useful to find some method to predict the expected life of an individual tube. The final goal has not been attained yet, but some useful information was obtained. It is thought that this information might be helpful for those people who will study this subject further.
Date: July 1, 1981
Creator: Zhao, Y.
Partner: UNT Libraries Government Documents Department

Two-dimensional beam-profile monitor using the Reticon MC510A array camera

Description: A quantitative two-dimensional beam profile may be obtained from a scintillator viewed by a Reticon camera which uses a 32 x 32 array of photodiodes as its sensing element. In this note, CAMAC-oriented data acquisition electronics which allow one either to transmit the profile to a computer, or to use the monitor in a stand-alone mode are described.
Date: August 1, 1981
Creator: Gottschalk, B.
Partner: UNT Libraries Government Documents Department

Quarkonium spectroscopy

Description: Recent experimental investigations of heavy quark-antiquark bound state systems are reviewed. Results from SPEAR on charmonium spectroscopy and from DORIS and CESR on bottomonium spectroscopy are presented. The current status of the search for top is also discussed.
Date: June 1, 1981
Creator: Scharre, D.L.
Partner: UNT Libraries Government Documents Department

Recent results from PEP

Description: Preliminary results are presented for the data taken by the MARK II and MAC collaborations at the PEP storage ring. Results include measurements of QED processes, limits on the weak couplings g/sub V/ and g/sub A/, limits on anomalous lepton production, the measurement of the tau lifetime, scale violation in inclusive hadron production, Monte Carlo independent tests of QCD using energy-energy correlations and single jet energy moments, measurements of the properties of three jet events, and measurements of proton, neutral kaon, lambda and proton pair yields.
Date: October 1, 1981
Creator: Hollebeek, R.
Partner: UNT Libraries Government Documents Department