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A high resolution beam profile monitor using Bremsstrahlung

Description: The development of efficient high energy linear colliders in the 1 TeV range requires final focus systems capable of producing beam spot sizes on the order of 1--20 nm, about three orders of magnitude smaller than those produced at the SLC. Although beam line designs exist which can, in principle, produce the required optics, the construction of quadrupoles with the size and precision required will be challenging. Field errors in these quads must be small and should be verified experimentally, which is difficult with existing technology. This paper describes a proposal to use bremsstrahlung from heavy targets to measure high energy beam profiles and positions with a resolution approaching a few nm. The method is also applicable to tests of other final focus systems (flat beams, plasma lenses) at lower energies. 6 refs., 3 figs., 1 tab.
Date: January 1, 1988
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

Preliminary tests of a second harmonic rf system for the intense pulsed neutron source synchrotron

Description: The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10/sup 12/ protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx. 3 x 10/sup 12/ ppp, depending somewhat on the available aperture. Accelerator improvements are being directed at (1) increasing beam intensities for neutron science, (2) lowering acceleration losses to minimize activation, and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. We are now proposing a third cavity for the RF system which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses by providing more RF voltage at maximum acceleration. This paper presents an outline of the expected benefits together with recent results obtained during low energy operation with one of the two existing cavities operating at the second harmonic (2f/sub 0/).
Date: January 1, 1983
Creator: Norem, J. & Brandeberry, F.
Partner: UNT Libraries Government Documents Department

In-situ maintenance of low-Z limiters in reactors

Description: In a reactor environment, the surface of a limiter or wall is primarily determined by the mechanism of erosion and deposition of surface material. It should be possible to use pellet injection to reduce net erosion to zero everywhere if low-Z materials are used for the surface. Erosion rates can, in general, be minimized by large area limiters and high plasma temperatures, which transmit power to the walls with less sputtering. Under ideal steady state conditions the wall surface is dominated by metallurgical effects in the wall.
Date: January 1, 1980
Creator: Norem, J.H.
Partner: UNT Libraries Government Documents Department

Can wall and limiter erosion be eliminated in fusion reactors

Description: A pump limiter system is described which is compatible with in-situ recoating of the limiter surface. The recoating could be done during normal tokamak operation. We have shown how this system is compatible with most of the constraints of fusion reactor operation and might provide a significant advantage over magnetic diverter and some other pump limiter geometries.
Date: October 1, 1981
Creator: Norem, J.H.
Partner: UNT Libraries Government Documents Department

Natural low Z coatings for fusion reactors

Description: Coating the walls of a vacuum chamber with Be or some other low Z material has been proposed as a possible solution to the problem of high Z impurities in plasmas. The properties of any coating will be highly dependent on (1) the nature of plasma impurity deposition on walls, and (2) radiation-induced solute segregation. The latter process can spontaneously produce low Z coatings in some alloys and drastically alter metallic interdiffusion in a reactor environment. We have studied the required parameters of coatings (thickness, composition, purity, etc.) and possible means of in situ deposition. We present results of a preliminary survey of coatings, substrates, and deposition methods whih are most compatible with reactor operation. We also outline experiments presently underway which will measure the stability of coatings in a radiation environment.
Date: January 1, 1979
Creator: Norem, J.H.
Partner: UNT Libraries Government Documents Department

Thin low Z coatings for plasma devices

Description: Coating the walls of the vacuum chamber with beryllium or some other low Z material has been proposed as a possible means of solving the problems of high Z influx into plasmas. We attempt to demonstrate that very thin, low Z coatings are compatible with the operation of plasma devices and beneficial to plasma performance. We determine that the thickness of coating material required is only about 10 monolayers. In a radiation environment, radiation-induced solute segregation should help to maintain the integrity of such thin coatings against diffusion and other processes. We discuss the properties of these thin coatings and possible means of in situ application and maintenance. Since deposition of plasma impurities on the walls will occur anyway, we discuss injection of solid pellets into the plasma as a direct way of introducing impurities which would ultimately serve as coating material.
Date: May 1, 1978
Creator: Norem, J. & Bowers, D.A.
Partner: UNT Libraries Government Documents Department

A beam profile monitor for small electron beams

Description: Measurement of beam properties at the foci of high energy linacs is difficult due to the small size of the waists in proposed and existing accelerators (1 nm {minus} 2 {mu}). This paper considers the use of bremsstrahlung radiation from thin foils to measure the size and phase space density these beams using nonimaging optics. The components of the system are described, and the ultimate resolution, evaluated theoretically for the case of the Final Focus Test Beam at Stanford Linear Accelerator Center, is a few nm. 13 refs., 4 figs. 1 tab.
Date: January 23, 1991
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

High Energy Physics Division semiannual report of research activities, January 1, 2000 - June 30, 2000.

Description: This report describes the research conducted in the High Energy Physics Division of Argonne National Laboratory during the period of January 1, 2000 through June 30, 2000. Topics covered here include experimental and theoretical particle physics, advanced accelerator physics, detector development, and experimental facilities research. Lists of Division publications and colloquia are included.
Date: January 16, 2001
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

An AGS experiment to test bunching for the proton driver of the muon collider.

Description: The proton driver for the muon collider must produce short pulses of protons in order to facilitate muon cooling and operation with polarized beams. In order to test methods of producing these bunches they have operated the AGS near transition and studied procedures which involved moving the transition energy {gamma} to the beam energy. They were able to produce stable bunches with RMS widths of {sigma} = 2.2-2.7 ns for longitudinal bunch areas of {minus}1.5 V-s, in addition to making measurements of the lowest two orders of the momentum compaction factor.
Date: April 27, 1998
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

Bent solenoids for spectrometers and emittance exchange sections.

Description: Bent solenoids can be used to transport low energy beams as they provide both confinement and dispersion of particle orbits. Solenoids are being considered both as emittance exchange sections and spectrometers in the muon cooling system as part of the study of the muon collider. They present the results of a study of bent solenoids which considers the design of coupling sections between bent solenoids to straight solenoids, drift compensation fields, aberrations, and factors relating to the construction, such as field ripple, stored energy, coil forces and field errors.
Date: March 26, 1999
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

e{sup +}e{sub {minus}} and ep options for the very large hadron collider.

Description: Although the linear collider is ultimately capable of higher energies, a circular e{sup +}e{sup {minus}} collider installed in the large tunnels of a Very Large Hadron Collider (VLHC) has attractive features, including very light magnet system and unchallenging vacuum requirements. An ep collider, built either in the 3 TeV booster or the large tunnel, could extend the HERA program beyond {radical}s {approximately} 1 TeV. Both machines could perhaps use the same rf system, first in the booster tunnel and then as part of the large collider.
Date: April 27, 1998
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

Beam stability in a 6 GeV synchrotron light source

Description: Future synchrotron radiation sources designed to produce low emittance electron beams for wigglers and undulators will present beam position control problems essentially similar to those encountered by users of existing accelerators, however tolerances will be tighter due to: (1) the small emittance (7 x 10/sup -9/ mrad) proposed for the electron beam and the correspondingly small emittances (sizes) of secondary photon beams, (2) the sensitivity of the electron beam closed orbit to quadrupole motion and dipole roll, (3) the high power levels associated with undulator and wiggler beams which will permit (and probably require) high precision and stability of the photon beam position measurements, in addition, (4) the large number of users on the roughly sixty beam lines will demand beams capable of producing the best experimental results. For the present paper, we assume the accelerator control function, which would initially involve making and coordinating all changes, would eventually evolve to setting and verifying the limits of user control: within these limits the beam position would be controlled by users. This paper describes the effects of motion of beam components (quads, rf cavities and dipoles) on the beam and considers the properties of a compensation system from the perspective of users. The system departs from standard practice in considering active perturbation of the electron beam to verify beam corrections. The effects of local closed orbit perturbations to direct undulator beams at different experimental setups are also considered. 8 refs., 3 figs.
Date: January 1, 1985
Creator: Norem, J.; Knott, M. & Rauchas, A.
Partner: UNT Libraries Government Documents Department

Proposed second harmonic acceleration system for the intense pulsed neutron source rapid cycling synchrotron

Description: The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10/sup 12/ protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx.3 x 10/sup 12/ ppp, depending somewhat on the available aperture. With the present good performance in mind, accelerator improvements are being directed at: (1) increasing beam intensities for neutron science; (2) lowering acceleration losses to minimize activation; and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. On the basis of preliminary measurements, we are now proposing a third cavity for the RF systems which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses.
Date: January 1, 1983
Creator: Norem, J.; Brandeberry, F. & Rauchas, A.
Partner: UNT Libraries Government Documents Department

Pulse compression system for the ANL 20 MeV linac

Description: This paper describes the pulse compression system being built on the Argonne 20 MeV electron linac. The system is designed to rotate the bunch from the present measured pulse length of 38 psec FWHM, to pulse lengths of 5 to 6 ps with the large instantaneous currents (1 to 4 kA) possible instantaneous current. This system was necessary to extend the study of reactive fragments of molecules to the time scale of a few picoseconds, in particular to examine the chemistry of electrons and ions before and during relaxation of the surrounding media. These experiments are not sensitive to the beam energy spread, High Energy Physics experiments studying wake fields have also been proposed using the short bunches and the facility was designed so that the wake field experiment could share the beam bunching system. The 20 MeV electron linac uses a double gap, 12th subharmonic prebuncher together with a one wavelength 1.3 Ghz prebuncher to produce a single pulse of 38 ps from one occupied rf bucket. Beam emittances of 15.7 mmmr have been measured for 40 nC of accelerated charge and 8 mmmr at 10 nC. The energy spread of dE/E = 1% (FWHM) has been measured at 40 nC. Thus the accelerated beam has excellent time structure, high current, and good emittance.
Date: January 1, 1986
Creator: Mavrogenes, G.; Norem, J. & Simpson, J.
Partner: UNT Libraries Government Documents Department

A high resolution, single bunch, beam profile monitor

Description: Efficient linear colliders require very small beam spots to produce high luminosities with reasonable input power, which limits the number of electrons which can be accelerated to high energies. The small beams, in turn, require high precision and stability in all accelerator components. Producing, monitoring and maintaining beams of the required quality has been, and will continue to be, difficult. A beam monitoring system which could be used to measure beam profile, size and stability at the final focus of a beamline or collider has been developed and is described here. The system uses nonimaging bremsstrahlung optics. The immediate use for this system would be examining the final focus spot at the SLAC/FFTB. The primary alternatives to this technique are those proposed by P. Chen / J. Buon, which analyses the energy and angular distributions of ion recoils to determine the aspect ratio of the electron bunch, and a method proposed by Shintake, which measures intensity variation of compton backscattered photons as the beam is moved across a pattern of standing waves produced by a laser.
Date: August 26, 1992
Creator: Norem, J.
Partner: UNT Libraries Government Documents Department

A laser strain gauge for accelerator targets.

Description: Multi megawatt accelerators can deliver sufficient power to a target to destroy it in a few pulses. In order to look at the response of solid and liquid targets under these high power pulses, we are developing optical methods of measuring surface deformations with time resolutions limited by laser pulse lengths. These methods can be used to examine the surfaces of solids and liquids during elastic deformation and unstable hydrodynamic flows. We present preliminary results of a system designed for target tests using the Brookhaven AGS and the Argonne CHM linac.
Date: July 17, 2001
Creator: Hassanein, A. & Norem, J.
Partner: UNT Libraries Government Documents Department

Thermoelastic response of suddenly heated liquid targets in high-power colliders.

Description: Thermoelastic response of liquid metal targets exposed to high-volumetric-energy deposition in times shorter than the target hydrodynamic response time (i.e., sound travel time) is of interest to several research areas, including targets for high-power accelerators such as the Spallation Neutron Source, muon collider targets, etc. Sudden energy deposition causes shock and rarefaction waves of magnitude {+-} {Delta}P that corresponds to an initial thermal pressure of tens of katm. Nevertheless a liquid subjected to a negative pressure is metastable. The problem of liquid target oscillations in the presence of large negative pressure, and the mechanism of fragmentation and its consequences, are considered in this paper.
Date: August 8, 2001
Creator: Hassanein, A.; Konkashbaev, I. & Norem, J.
Partner: UNT Libraries Government Documents Department

Transverse focussing using plasma wake fields

Description: Dense particle beams traveling in plasmas can produce very high electric and magnetic fields, and these fields can be used to accelerate and focus particles. The effects on trailing beams and self focusing can be strong and nonlinear. This paper discusses two aspects of self pinching beams: (1) the production of beams which do not self pinch, and (2) a short focal length plasma lens which uses self pinching to reduce beam sizes at the interaction point of a linear collider. As an example, a final focus system for the Stanford Linear Collider is considered. It is shown how the luminosity could be increased using this system.
Date: January 1, 1987
Creator: Cline, D.B.; Cole, B.; Rosenzweig, J. & Norem, J.
Partner: UNT Libraries Government Documents Department

A plasma lens for a linear collider final focus

Description: High density relativistic beams propagating in a plasma are affected by fields induced by plasma motion. We consider the possible use of a plasma cell very close to the interaction point of a linear collider where the self-pinch induced in the relativistic beams can be used to increase the luminosity of colliding beams. We describe the benefits of this self-pinch, as well as some engineering details on the production of the required plasma. 18 refs., 5 figs., 1 tab.
Date: January 1, 1987
Creator: Norem, J.; Cline, D.B.; Cole, B. & Rosenzweig, J.
Partner: UNT Libraries Government Documents Department

Experimental measurement of nonlinear plasma wake-fields

Description: We report direct high resolution observation of nonlinear steepened plasma waves excited in the wake of an intense, self-pinched electron beam. Oscillators in both accelerating and deflecting fields are measured, and analyzed in the context of linear and nonlinear plasma wave theory. The degree of nonlinearity in the wake-fields is shown to be consistent with analytical predictions of the beam self-pinching. The impact of these results on plasma acceleration and focusing schemes is discussed. 15 refs., 4 figs.
Date: January 1, 1989
Creator: Rosenzweig, J.B.; Schoessow, P.; Cole, B.; Gai, W.; Konecny, R.; Norem, J. et al.
Partner: UNT Libraries Government Documents Department

A high energy e{sup +}e{sup {minus}} collider in a ``really large`` tunnel

Description: Recent developments in tunneling technology imply that it is possible to consider much larger tunnels for high energy circular colliders in the future. Tunnels with diameters of 200 km are being considered for a low field hadron collider called the Really Large Hadron Collider (RLHC). This tunnel might be produced for a cost of about 1000 $/m. An e{sup +}e{sup -} collider in this tunnel could perhaps study {ital t{anti t}} production at threshold with good resolution, Higgs production and e/p collisions at high energy. This note considers some of the parameters and issues of such a machine.
Date: December 31, 1996
Creator: Norem, J. & Keil, E.
Partner: UNT Libraries Government Documents Department

High Energy Physics Division semiannual report of research activities. Semi-annual progress report, July 1, 1995--December 31, 1995

Description: This report describes the research conducted in the High Energy Physics Division of Argonne National Laboratory during the period July 1, 1995 - December 31, 1995. Topics covered here include experimental and theoretical particle physics, advanced accelerator physics, detector development, and experimental facilities research. Lists of division publications and colloquia are included.
Date: October 1, 1996
Creator: Norem, J.; Bajt, D.; Rezmer, R. & Wagner, R.
Partner: UNT Libraries Government Documents Department