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Beam-beam deflections to measure size spot and offset at SLC IP

Description: As soon as two SLC beams make it to the intersection region, both transverse offsets, spot sizes and shapes can be extracted from the pattern of angular deflections produced by the electromagnetic interaction of the two beams, as one is scanned across the other. These deflections, measured in two high resolution Beam Position Monitors (BPM) mounted symmetrically on both sides of the intersection point, will produce detectable signals allowing spot sizes to be tuned, even with the very low luminosities expected at turn on. They will also furnish a good signal to monitor beam centering and will therefore become an important part of the FFS feedback system. This note summarizes the formulae which will allow us to correlate BPM offset readings with the properties of the two beams, and describes the range and limitations of the technique in the case of SLC.
Date: June 10, 1985
Creator: Bambade, P.
Partner: UNT Libraries Government Documents Department

Application of GPS in a high precision engineering survey network

Description: A GPS satellite survey was carried out with the Macrometer to support construction at the Stanford Linear Accelerator Center (SLAC). The network consists of 16 stations of which 9 stations were part of the Macrometer network. The horizontal and vertical accuracy of the GPS survey is estimated to be 1 to 2 mm and 2 to 3 mm respectively. The horizontal accuracy of the terrestrial survey, consisting of angles and distances, equals that of the GPS survey only in the ''loop'' portion of the network. All stations are part of a precise level network. The ellipsoidal heights obtained from the GPS survey and the orthometric heights of the level network are used to compute geoid undulations. A geoid profile along the linac was computed by the National Geodetic Survey in 1963. This profile agreed with the observed geoid within the standard deviation of the GPS survey. Angles and distances were adjusted together (TERRA), and all terrestrial observations were combined with the GPS vector observations in a combination adjustment (COMB). A comparison of COMB and TERRA revealed systematic errors in the terrestrial solution. A scale factor of 1.5 ppM +- .8 ppM was estimated. This value is of the same magnitude as the over-all horizontal accuracy of both networks. 10 refs., 3 figs., 5 tabs.
Date: April 1, 1985
Creator: Ruland, R. & Leick, A.
Partner: UNT Libraries Government Documents Department

Effects of slots/holes in disks on frequencies of TM/sub 01/ and EH/sub 11/ waves in the disk-loaded waveguide

Description: The increase in the BBU threshold current is very important for the high and medium energy electron linacs because of a larger operating current attainable or a smaller emittance available at certain operating current. For this purpose, many means can be used, among which the improvement in the accelerating structure itself is always fundamental. SLAC's three-meter long section is unique with truly constant gradient performance. The theoretical analyses and operating experiences at SLAC have indicated that detuning the Nos. 3, 4 and 5 cavities of some sections by 2 or 4 MHz for TM/sub 01/ wave had considerably raised the BBU threshold current. A method of opening four holes symmetrically distributed on disks as described in detail will get the benefits in improvement of BBU threshold current.
Date: March 1, 1985
Creator: Yao, C.G.
Partner: UNT Libraries Government Documents Department

Detector problems at the SSC

Description: During the last couple of years there has been considerable concern expressed among the US high energy community as to whether detector limitations would prevent one from being able to fully exploit a luminosity of 10/sup 33/ cm/sup -2/ sec/sup -1/ at a hadron-hadron high energy collider. As a result of these concerns, a considerable amount of work has been done recently in trying to understand the nature of potential difficulties and the required R and D that needs to be performed. A lot of this work has been summarized in the 1984 DPF Summer Study at Snowmass. This paper attempts to review some of these results. This work is limited to the discussion of detector problems associated with the study of high energy hadron-hadron collisions. We shall start with the discussion of the desirable features of the detectors and of the SSC environment in which they will have to work. After a brief discussion of the model 4..pi.. detectors, we shall discuss specific detector aspects: lepton identification, tracking, calorimetry and computing and triggering. We shall end with some remarks about possible future course of events. 15 refs., 10 figs.
Date: February 1, 1985
Creator: Wojcicki, S.G.
Partner: UNT Libraries Government Documents Department

Collinear wake field acceleration

Description: In the Voss-Weiland scheme of wake field acceleration a high current, ring-shaped driving bunch is used to accelerate a low current beam following along on axis. In such a structure, the transformer ratio, i.e., the ratio of maximum voltage that can be gained by the on-axis beam and the voltage lost by the driving beam, can be large. In contrast, it has been observed that for an arrangement in which driving and driven bunches follow the same path, and where the current distribution of both bunches is gaussian, the transformer ratio is not normally greater than two. This paper explores some of the possibilities and limitations of a collinear acceleration scheme. In addition to its application to wake field acceleration in structures, this study is also of interest for the understanding of the plasma wake field accelerator. 11 refs., 4 figs.
Date: April 1, 1985
Creator: Bane, K.L.F.; Chen, P. & Wilson, P.B.
Partner: UNT Libraries Government Documents Department

Computer control of rf at SLAC

Description: The Stanford Linear Accelerator is presently upgraded for the SLAC Linear Collider project. The energy is to be increased from approximately 31 GeV to 50 GeV. Two electron beams and one positron beam are to be accelerated with high demands on the quality of the beams. The beam specifications are shown. To meet these specifications, all parameters influencing the beams have to be under tight control and continuous surveillance. This task is accomplished by a new computer system implemented at SLAC which has, among many other functions, control over rf accelerating fields. 13 refs., 8 figs., 2 tabs.
Date: March 1, 1985
Creator: Schwarz, H.D.
Partner: UNT Libraries Government Documents Department

Comparison of the plasma beat wave accelerator and the plasma wake field accelerator

Description: In this paper we compare the Plasma Beat Wave Accelerator and Plasma Wake Field Accelerator. We show that the electric fields in the plasma for both schemes are very similar, and thus the dynamics of the driven beams are very similar. The differences appear in the parameters associated with the driving beams. In particular to obtain a given accelerating gradient, the Plasma Wake Field Accelerator has a higher efficiency and a lower total energy for the driving beam. 7 refs., 2 tabs.
Date: March 1, 1985
Creator: Chen, P. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

Control problems in very large accelerators

Description: There is no fundamental difference of kind in the control requirements between a small and a large accelerator since they are built of the same types of components, which individually have similar control inputs and outputs. The main difference is one of scale; the large machine has many more components of each type, and the distances involved are much greater. Both of these factors must be taken into account in determining the optimum way of carrying out the control functions. Small machines should use standard equipment and software for control as much as possible, as special developments for small quantities cannot normally be justified if all costs are taken into account. On the other hand, the very great number of devices needed for a large machine means that, if special developments can result in simplification, they may make possible an appreciable reduction in the control equipment costs. It is the purpose of this report to look at the special control problems of large accelerators, which the author shall arbitarily define as those with a length of circumference in excess of 10 km, and point out where special developments, or the adoption of developments from outside the accelerator control field, can be of assistance in minimizing the cost of the control system. Most of the first part of this report was presented as a paper to the 1985 Particle Accelerator Conference. It has now been extended to include a discussion on the special case of the controls for the SSC.
Date: June 1, 1985
Creator: Crowley-Milling, M.C.
Partner: UNT Libraries Government Documents Department

Accelerator physics measurements at the damping ring

Description: Besides the optics measurements described elsewhere, machine experiments were done at the SLC damping ring to determine some of its parameters. The synchrotron radiation energy loss which gives the damping rates was measured by observing the rf-voltage dependence of the synchronous phase angle. The emittance was obtained from the synchrotron light monitor, scraper measurements and by extracting the beam through a doublet and measuring its size for different quadrupole settings. Current dependent effects such as parasitic mode losses, head tail instabilities, synchrotron and betatron frequency shifts were measured to estimate the impedance. Rf-cavity beam loading and its compensation were also studied and ion collection was investigated. All results agree reasonably well with expectations and indicate no limitations to the design performance.
Date: May 1, 1985
Creator: Rivkin, L.; Delahaye, J.P.; Wille, K.; Allen, M.; Bane, K.; Fieguth, T. et al.
Partner: UNT Libraries Government Documents Department

Beam position monitor readout and control in the SLC linac

Description: A beam position monitoring system has been implemented in the first third of the SLC linac which provides a complete scan of the trajectory on a single beam pulse. The data is collected from the local micro-computers and viewed with an updating display at a console or passed on to application programs. The system must operate with interlaced beams so the scans are also interlaced, providing each user with the ability to select the beam, the update rate, and the attenuation level in the digitizing hardware. In addition each user calibrates the hardware for his beam. A description of the system architecture will be presented. 6 refs., 4 figs.
Date: April 1, 1985
Creator: Bogart, J.; Phinney, N.; Ross, M. & Yaffe, D.
Partner: UNT Libraries Government Documents Department

Beam emittance and beam disruption

Description: Beam disruption during the collision of intense relativistic bunches has been studied by R. Hollebeek. In the case of oppositely charged bunches, focussing effects occur causing a decrease in the effective bunch cross section, and thereby an increase of luminosity by an enhancement factor H. The term disruption derives from the fact that the beam emittance changes markedly during the collision. 1 ref., 1 fig., 1 tab.
Date: June 1, 1985
Creator: Hollebeek, R. & Minten, A.
Partner: UNT Libraries Government Documents Department

Diagnostic for dynamic aperture

Description: In large accelerators and low beta colliding beam storage rings, the strong sextupoles, which are required to correct the chromatic effects, produce strong nonlinear forces which act on particles in the beam. In addition in large hadron storage rings the superconducting magnets have significant nonlinear fields. To understand the effects of these nonlinearities on the particle motion there is currently a large theoretical effort using both analytic techniques and computer tracking. This effort is focused on the determination of the 'dynamic aperture' (the stable acceptance) of both present and future accelerators and storage rings. A great deal of progress has been made in understanding nonlinear particle motion, but very little experimental verification of the theoretical results is available. In this paper we describe 'dynamic tracking', a method being studied at the SPEAR storage ring, which can be used to obtain experimental results which are in a convenient form to be compared with the theoretical predictions.
Date: April 1, 1985
Creator: Morton, P.L.; Pellegrin, J.L.; Raubenheimer, T.; Rivkin, L.; Ross, M.; Ruth, R.D. et al.
Partner: UNT Libraries Government Documents Department

Data acquisition system for SLD

Description: This paper describes the data acquisition system planned for the SLD detector which is being constructed for use with the SLAC Linear Collider (SLC). An exclusively FASTBUS front-end system is used together with a VAX-based host system. While the volume of data transferred does not challenge the band-width capabilities of FASTBUS, extensive use is made of the parallel processing capabilities allowed by FASTBUS to reduce the data to a size which can be handled by the host system. The low repetition rate of the SLC allows a relatively simple software-based trigger. The principal components and overall architecture of the hardware and software are described.
Date: May 1, 1985
Creator: Sherden, D.J.
Partner: UNT Libraries Government Documents Department

Additional muon calculations for the SLC positron source

Description: This note is an update to the muon calculations presented in CN-221 and takes into account: (1) a more complete muon production and transport model, including an estimate of wide angle production based on experimental data, (2) additional earth shielding that will be added on top and both sides of the 2/3 tunnel areas, and (3) a detailed analysis of the earth profile as it pertains to shielding in the direction of the SLAC site boundary. The highest annual dose at the SLAC boundary is found to be 13 mrem/year (4000 hours of operation at 50 kW), and this occurs at a horizontal angle of 0 degrees and a vertical angle of 3.6 degrees relative to the incident beam direction. Although the shielding criteria is 10 mrem/year at the site boundary, the radiation transport model becomes somewhat conservative at large distances from the shield, which should bring the 13 mrem/year number actually well below the criteria. This point is also about 28 feet above the roadway. Extension of this line may strike the ground in the Christmas tree farm beyond the SLAC boundary but there will be additional attenuation due to distance. We do not recommend that any additional shielding be added at this time. 4 refs., 1 fig.
Date: April 23, 1985
Creator: Nelson, W.R. & McCall, R.C.
Partner: UNT Libraries Government Documents Department

dE/dx electronics for MARK II experiment at SLAC

Description: This paper describes a 100 MHz pulse digitizer for dE/dx measurements on the MARK II drift chamber at SLAC. The electronics provides the read-out of the detector's 5832 sense based on a 16-channel FASTBUS module. The basic element of the module is the TRW 6-bit Flash-ADC.
Date: October 1, 1985
Creator: Bernstein, D.; Boyarski, A.; Coupal, D.; Feldman, G. & Paffrath, L.
Partner: UNT Libraries Government Documents Department

Energy deposition and its effects on the E/sup +/ capture section at Sector 20

Description: The temperature profile and resulting stresses and strains of the capture section (positron source accelerator section) at Sector 20 were investigated. The Electron-Gamma Shower program, Version 4 (EGS4) was used to determine energy deposition. For a 31.68 kW, 33 GeV electron beam, the rate of energy deposition in the first accelerator disk downstream from the 90/10 tantalum-tungsten positron target was determined to be 0.56 kW. The calculated resulting temperature difference from the inner disk diameter to the outer disk diameter is 49.4/sup 0/F. The inner diameter could then reach a temperature of 169.5/sup 0/F. The maximum stress produced in this first disk would be a compressive stress of 4374 psi, also at the inner diameter.
Date: April 29, 1985
Creator: Kramer, J.F.
Partner: UNT Libraries Government Documents Department

Annual environmental monitoring report, January-December 1984

Description: Non-radioactive monitoring program involved: repair of a leaking waste paint and solvent tank, installation of a pretreatment facility for liquid effluents from a plating shop; and construction discharge. Radioactivity was monitored for air with comparisons to the average annual population dose from neutron radiation and tritium in the waste water effluents.
Date: March 1, 1985
Partner: UNT Libraries Government Documents Department

Gluonium candidates from hadronic and e/sup +/e/sup -/ interactions

Description: The experimental approaches exploited in the search for gluonia that are deemed most promising are briefly described, both in hadron-hadron collisions and heavy quarkonium decay. The presently available evidence is summarized for those states that have been claimed as possible gluonia. Proceeding in the order of lowest-mass expectation, categorization is done only in terms of definitive (or putative) J/sup PC/ assignments. 51 refs., 16 figs., 3 tabs. (LEW)
Date: December 1, 1985
Creator: Heusch, C.A.
Partner: UNT Libraries Government Documents Department

Factorization of the Drell-Yan cross section

Description: We state the weak and strong factorization theorems for the Drell-Yan cross section and outline the ingredients involved in their proof. We also discuss the physical picture implied by the factorization results and its phenomenological consequences.
Date: April 1, 1985
Creator: Bodwin, G.T.; Brodsky, S.J. & Lepage, G.P.
Partner: UNT Libraries Government Documents Department

Hadron spectroscopy

Description: Heavy quark systems and glueball candidates, the particles which are relevant to testing QCD, are discussed. The review begins with the heaviest spectroscopically observed quarks, the b anti-b bound states, including the chi state masses, spins, and hadronic widths and the non-relativistic potential models. Also, P states of c anti-c are mentioned. Other heavy states are also discussed in which heavy quarks combine with lighter ones. The gluonium candidates iota(1460), theta(1700), and g/sub T/(2200) are then covered. The very lightest mesons, pi-neutral and eta, are discussed. 133 refs., 24 figs., 16 tabs. (LEW)
Date: October 1, 1985
Creator: Cooper, S.
Partner: UNT Libraries Government Documents Department

GIANT: a computer code for General Interactive ANalysis of Trajectories

Description: 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 organization of this program and some of the recent applications of the procedures will be described in this paper.
Date: April 1, 1985
Creator: Jaeger, J.; Lee, M.; Servranckx, R. & Shoaee, H.
Partner: UNT Libraries Government Documents Department

Gluonia. [Xi-2200 resonances]

Description: The postulated existence of hadrons with no quark content, implied by the non-Abelian nature of quantum chromodynamics, has been the object of much experimental activity. Recent data from radiative psi decay permit a confrontation of available evidence with the most simple-minded criteria for their appearance. In the absence of compellingly positive evidence we give a rating of the relative merits of several possible candidates. 36 references, 17 figures.
Date: January 1, 1985
Creator: Heusch, C.A.
Partner: UNT Libraries Government Documents Department

Search for heavy neutrinos produced in e/sup +/e/sup -/ annihilation

Description: We report a search for long-lived heavy neutrinos produced by the neutral weak current in e/sup +/e/sup -/ annihilation at 29 GeV at PEP. Data from the Mark II detector are examined for evidence of events with one or more separated vertices in the radial range of 2 mm to 10 cm. No events were found that were consistent with the hypothesis of heavy neutrino production, eliminating the possibility of heavy neutrinos with decay lengths of 1 to 20 cm in mass range 1 to 13 GeV/c/sup 2/. 11 refs.
Date: May 1, 1985
Creator: Feldman, G.J.
Partner: UNT Libraries Government Documents Department