CERN currently delivers antiprotons for trapping experiments with the antiproton decelerator (AD), which slows the antiprotons down to about 5 MeV. This energy is currently too high for direct trapping, and thick foils are used to slow down the beam to energies which can be trapped. To allow further deceleration to similar to 100 keV, CERN is initiating the construction of ELENA, consisting of a ring which will combine rf deceleration and electron cooling capabilities. We describe a simple frictional cooling scheme that can serve to provide significantly improved trapping efficiency, either directly from the AD or first using a standard deceleration mechanism (induction linac or rf quadrupole). This scheme could be implemented in a short time. The device itself is short in length, uses accessible voltages, and at reasonable cost could serve in the interim before ELENA becomes operational, or possibly in lieu of ELENA for some experiments. Simple theory and simulations provide a preliminary assessment of the concept and its strengths and limitations, and highlight important areas for experimental studies, in particular to pin down the level of multiple scattering for low-energy antiprotons. We show that the frictional cooling scheme can provide a similar energy spectrum to that of ELENA, but with higher transverse emittances.

The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented.

The history of the people and circumstances surrounding three papers will be presented. The first is the L.N. Cooper, R. L. Mills and A. M. Sessler, "Possible Superfluidity of a System of Strongly Interacting Fermions", in which the possibility of He-3 being a superfluid was suggested (although, it seemed not to be the case as only S-states were considered). The second is V.J. Emery and A. M. Sessler, "Possible Phase Transition in Liquid He-3", in which a definite prediction of superfluidity was proposed (in contrast with the conclusion of the earlier paper since here D-states were considered). And the third is A. E. Glassgold and A. M. Sessler, "Flow Properties of Superfluid System of Fermions", in which the flow properties of superfluid He-3 were examined. Although the emphasis will be on the physicists, their background, educational experiences, and surroundings, some attention will be given to the physics in each of these papers for it was-after all-the physics that stimulated, along with the work of others, further theoretical work and, most importantly, the exceptional, and ultimately successful, experimental efforts of the following decade.

During the process of ion beam crystallization, the main heating source is Intra-beam scattering (IBS), in which the Coulomb collisions among particles lead to a growth in the 6D phase space volume of the beam. The results of molecular dynamics (MD) simulation have shown an increase of heating rate as the temperature is increased from absolute zero, but then a peak in the heating rate, and subsequent decrease with ever increasing temperature. [J. Wei, H. Okamoto, and A. M. Sessler, Phys. Rev. Lett. 80, 2606 (1994)]. This phenomenon has been carefully studied by Y. Yuri, H. Okamoto, and H. Sugimoto [Y. Yuri, H. Okamoto, and H. Sugimoto, J. Phys. Soc. Jpn. 78, 124501 (2009)]. On the other hand, in the traditional IBS theory valid at high temperatures, heating rate is an ever increasing as the temperature becomes lower and lower. [A. Piwinski, Lect. Notes Phys. 296, 297 (1988)]. In this paper we attempt to extend the traditional IBS theory valid at high temperatures to relatively low temperature range, by including some many body effects in the traditional IBS theory. In particular we take into account the static and dynamic effect of the self-electromagnetic field of the beam. We shall show how these effects modify the traditional IBS theory, and present the evaluation of IBS heating rate of an ion beam in the low temperature range.

During the process of ion beam crystallization, the main heating source is Intra-beam scattering (IBS), in which the Coulomb collisions among particles lead to a growth in the 6D phase space volume of the beam. The results of molecular dynamics (MD) simulation have shown an increase of heating rate as the temperature is increased from absolute zero, but then a peak in the heating rate, and subsequent decrease with ever increasing temperature. [J. Wei, H. Okamoto, and A. M. Sessler, Phys. Rev. Lett. 80, 2606 (1994)]. This phenomenon has been carefully studied by Y. Yuri, H. Okamoto, and H. Sugimoto [Y. Yuri, H. Okamoto, and H. Sugimoto, J. Phys. Soc. Jpn. 78, 124501 (2009)]. On the other hand, in the traditional IBS theory valid at high temperatures, heating rate is an ever increasing as the temperature becomes lower and lower. [A. Piwinski, Lect. Notes Phys. 296, 297 (1988)]. In this paper we attempt to extend the traditional IBS theory valid at high temperatures to relatively low temperature range, by including some many body effects in the traditional IBS theory. In particular we take into account the static and dynamic effect of the self-electromagnetic field of the beam. We shall show how these effects modify the traditional IBS theory, and present the evaluation of IBS heating rate of an ion beam in the low temperature range.

Edward Teller died on September 9, 2003 in Stanford, California at the age of 95. He was both one of the great theoretical physicists of the twentieth century and a leading figure in the development of nuclear weapons and broader defense advocacy. Teller's work in physics, spanning many decades of the twentieth century, includes some of the most fundamental insights in the quantum behaviors of molecules and their spectra, nuclei, surfaces, solid state and spin systems, and plasmas. In the defense arena, Teller is best known for his key insight that made thermonuclear weapons possible. Teller was both a great scientific collaborator and physics teacher at all levels, known for his openness, generosity, personal warmth, and powerful physical intuition. Many of his graduate students went on to illustrious careers.

Coupling resonances can be used to control the phase–space configuration of a charged-particle beam. Here we study a compact storage ring, which enables one to achieve a wide variety of emittance manipulations. A simple analytic model and numerical examples are given to demonstrate the fundamental features of the coupled beam motion near resonance. As a possible application of the present idea, free-electron lasers (FELs) are studied. It is shown that, by employing a nonlinear coupling resonance, the phase–space distribution of an electron beam can be optimized for high FEL gain. A three-dimensional simulation code is used to confirm that the “conditioned” electron beam from the coupling storage ring improves the performance of the subsequent FEL system.

During the past several decades, beam crystallization has been studied both theoretically and experimentally. Theoretical investigations have been numerical, mainly using computer modeling based on the method of molecular dynamics (MD), and analytical, based on phonon theory. Experimental investigations involve both ion storage rings and ion traps using both electron and laser beam cooling. Topics of interests include crystal stability in various accelerator lattices and under different beam conditions, colliding crystalline beams, crystalline beam formation in shear-free ring lattices with both magnets and electrodes, experimental simulation of alternating-gradient conditions with an ion trap, tapered cooling and coupled cooling, and beam dynamics at different temperature regime as the beam is cooled from high to low temperature. In this paper, we first review theoretical approaches and major conclusions pertaining to beam crystallization. Then, we analyze conditions and methods of the various major experiments. Finally, we discuss, both theoretically and experimentally, some improvements, open questions, and challenges in beam crystallization.

LBL-27035 ~.~ ITl1 Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA I Accelerator & Fusion Research Division Presented at the CERN Accelerator School, Chester, U.K., April 6-13, 1989 High-Power, High-Efficiency FELs A.M. Sessler April 1989 TWO-WEEK LOAN COpy This is which a Library Circulating Copy may be borrowed for two weeks. Prepared for the U.S. Department of Energy under Contract Number DE-AC03-76SF00098

LBL·38278 UC·427 ERNEST ORLANDO LAWRENCE BERKELEY NATIONAL LABORATORY Methods of Beam Cooling A. M. Sessler Accelerator and Fusion Research Division February 1996 Presented at the 31st Workshop: Crystalline Beams and Related Issues, Erice, Italy, November 11·21, 1995, and to be published in the Proceedings a. CD (J'I IS! '< I'\) OJU r r r CD I lJJ co co I'\)

We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results.

A free-electron laser (FEL) two-beam accelerator (TBA) is proposed, in which the FEL interaction takes place in a series of drive cavities, rather than in a waveguide. Each drive cavity is “beat-coupled” to a section of the accelerating structure. This standing-wave TBA is investigated theoretically and numerically, with analyses included of microwave extraction, growth of the FEL signal through saturation, equilibrium longitudinal beam dynamics following saturation, and sensitivity of the microwave amplitude and phase to errors in current and energy. It is found that phase errors due to current jitter are substantially reduced from previous versions of the TBA. Analytic scalings and numerical simulations are used to obtain an illustrative TBA parameter set.

I UCRL-16440 University of California Ernest O. Lawrence Radiation Laboratory INSTABILITIES OF RELATIVISTIC PARTICLE BEAMS TWO-WEEK LOAN COpy This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call Tech. Info. Division, Ext 5545 !I I I Berkeley, California il 1 r '