36965886
A traveling wave accelerator with HOM outcouplers for FELs
The application to FELs (free-electron lasers) of RF electron guns with laser-driven photocathodes has opened the door to developing efficient optical FELs. The next task is to develop accelerator structures which can transport such beams with a minimum of beam degradation. A low-cost approach to this using four 1.26-m constant gradient (CG) TW sections driven in parallel by a SLAC 5045 klystron is suggested. Using CG sections makes the higher order modes incoherent due to the linearly decreasing group velocity along the structure. Together with incorporating higher-order-mode outcouplers, this system is predicted to accelerate 1 nC per micropulse, 0.4 A per macropulse to 75 MeV from an injection energy of 5 MeV. Emittance growth is predicted to be 5 mm-mr.<<ETX>>
5840211
Fabrication and Tolerance Issues and their Influence on Multi-Bunch BBU and Emittance Dilution in the Construction of X-Band RDDS Linacs for the NLC
The main linacs of the Next Linear Collider (NLC) will contain several thousand X-band RDDS (Rounded Damped Detuned Structures). The transverse wakefield in the structures is reduced by detuning the modal frequencies such that they destructively interfere and by four damping manifolds per structure which provide weak damping. Errors in the fabrication of the individual cells and in the alignment of the cells will reduce the cancellation of the modes. Here, the authors calculate the tolerances on random errors in the synchronous frequencies of the cells and the cell-to-cell alignment.
2871115
A spectral function method applied to the calculation of the wake function for the NLCTA
The equivalent circuit representation of the dipole modes of the SLAC damped detuned structure (DDS) which is being fabricated at LAC has been analyzed by three different methods. The first two are based upon a modal analysis: in the first, damped modes are found by a first order perturbation in the cell to damping manifold coupling strength; while in the second, preferred when the coupling strength is large (as is the case for the SLAC structure) they are determined exactly (a time consuming procedure). The third method, which the authors report here, expresses the wake as a modal sum for modes whose frequencies place them outside the propagation bands of the manifolds (a minor contribution) plus a Fourier like integral of a spectral function over the propagation band of the manifolds (the major contribution). They will present comparisons to previous calculations, assessment of appropriate domains of applicability, and applications to the SLAC structure with matched and mismatched manifold terminations.
124416371
CTF3 Drive-Beam Injector Design
The Two-Beam Accelerator concept is one of the most promising methods for producing RF power for future linear colliders. In particular it allows upgrades to multiTeV energies. One of its challenges is the production of the high current drive beam, which as it passes through decelerating structures, produces RF power for acceleration of the main beam. These challenges must be studied at a smaller scale test facility.
122827069
High current RF accelerator for FEL applications
It is shown that the HCRF (high-current radio-frequency) concept promises to achieve an average gradient on the orders of 20 MV/m using standard conductors and low Q cavities. Therefore, relatively low technology, robust construction techniques can be used for the accelerator, and risk is reduced accordingly. Initial analysis of two critical issues, accelerator efficiency and beam quality, is presented. The concept uses high peak power (approximately 10-GW) microwaves to drive low-Q RF cavities. The cavities are designed to selectively damp modes that lead to transverse beam-breakup instabilities in the accelerator. The high power microwaves will be generated in external devices such as phase stable klystron amplifiers driven by relativistic electron beams. The HCRF accelerator will produce a 200-MeV FEL (free-electron laser) quality electron beam with 1500 2-kA, 50-ps micropulses contained in 50-A (average current), 3- mu s macropulses that are repeated every 300 mu s. Average electron beam power into the wiggler will be 100 MW, and the overall duty factor is 2.5*10/sup -4/.<<ETX>>
31326344
Achievement of Bevalac Rapid Mode Switching
Rapid changes of ion, intensity, beam line, and output energy between two modes have been achieved. The techniques for switching among the Bevalac's several injectors are described. Energy level limits at the output (for q/A=1/2) are 470-2100 MeV/n (high power) or 50-1050 MeV/n (low power). Depending on specific field value differences, the total time required for a mode change is less than one minute. This mode of operation greatly improves program efficiency in interleaving medical and nuclear science programs at the Bevalac.
121351026
Three and higher order rapidity distributions in pp collisions at 200 GeV/c
Abstract Three-particle rapidity distributions have been studied for different charged multiplicities in pp interactions at 200 GeV/ c . Appropriately defined semi-inclusive three-particle correlations are found to be sufficiently small, leading us to conclude that the three-particle density can be expressed in terms of one- and two-particle densities. For events with more than four charged particles, a superposition approximation for the three-particle density holds surprisingly well. This approximation enables us to express all higher order rapidity distributions in terms of one- and two-particle distributions alone.
17714212
The NLC positron source
A baseline design for the NLC positron source based on the existing SLC positron system is described. The proposed NLC source consists of a dedicated S-band electron accelerator, a conventional positron production and capture system utilizing a high-Z target and an adiabatic matching device, and an L-band positron linac. The invariant transverse acceptance of the capture system is 0.06 m/spl middot/rad, ensuring an adequate positron beam intensity for the NLC.
117016085
Inclusive production of lambda and neutral kaon in K−p interactions at 3.93 GeV/c and 14.3 GeV/c
SummaryLambda and neutral-kaon production is studied in K−p interactions at 3.93 and 14.3 GeV/c. Topological inclusive cross-sections are given at both energies. Invariant cross-sections for lambdas and neutral kaons are presented as a function of the Feynmanx-variable and are found to decrease in magnitude and vary their shapes with energy. The

$$AK\overline K $$

 production, which represents (9±2)% and (29±3)% of the lambda inclusive cross-section at 3.93 GeV/c and 14.3 GeV/c respectively, yields mainly backward lambdas. The shapes of the transverse-momentum invariant distributions vary withx, but are roughly independent of energy. The lambda polarization is studied as a function ofx at both incident momenta: for fast lambdas it is negative, as observed in reactions where nucleon exchange is dominant.RiassuntoSi studia la produzione di particelle lambda e di kaoni neutri nelle interazioni K−p a 3.93 e 14.3 GeV/c. Per entrambi i valori dell'energia si danno le sezioni d'urto inclusive topologiche. Si presentano le sezioni d'urto invarianti per particelle lambda e kaoni neutri in funzione della variabilex di Feynman e si trova che diminuiscono in grandezza e cambiano di forma con l'energia. La produzione di

$$AK\overline K $$

, che rappresenta il (9±2)% e il (29±3)% della sezione d'urto inclusiva delle particelle lambda rispettivamente a 3.93 GeV/c e 14.3 GeV/c, dà per lo più particelle lambda che vanno all'indietro. Gli andamenti delle distribuzioni invarianti dell'impulso trasversale variano conx, ma sono approssimativamente indipendenti dall'energia. Si studia la polarizzazione delle particelle lambda in funzione dix per entrambi i valori dell'impulso incidente: per particelle lambda veloci è negativa, come si è osservato in reazioni in cui predomina lo scambio di nucleoni.РезюмеИсследуется рождение ламбда и нейтрального каона в K−p взаимодействиях при 3.93 ГэВ/с и 14.3 ГэВ/с. При обеих энергиях приводятся топологические инклюзивные поперечные сечения. Инвариантные поперечные сечения для ламбда и нейтральных каонов представлены в виде функции фейнмановскойx переменной. Получено, что поперечные сечения уменьшаются по величине и изменяют свою форму с энергией.

$$AK\overline K $$

 рождение, которое составляет соответственно (9±2)% и (29±3)% ламбда инклюзивного поперечного сечения при 3.93 ГэВ/с и 14.3 ГэВ/с, образует в основном ламбда-частицы, летящие в обратном направлении. Формы инвариантных распределений для поперечного импульса изменяются с «x», но вгрубом приближении не зависят от энергии. Исследуется поляризация ламбда, как функцияx для обоих начальных испульсов: для быстрых ламбда-частиц поляризация отрицательная, как наблюдается в реакциях, где доминирует нуклонный обмен.
116487099
The trace of the energy momentum tensor and the lattice interaction measure at finite temperature
55614129
Codes and supersymmetry in one dimension
Adinkras are diagrams that describe many useful supermultiplets in D=1 dimensions. We show that the topology of the Adinkra is uniquely determined by a doubly even code. Conversely, every doubly even code produces a possible topology of an Adinkra. A computation of doubly even codes results in an enumeration of these Adinkra topologies up to N=28, and for minimal supermultiplets, up to N=32.