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in creator/contributor: "Ng, K. Y."

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Computer program for calculating the resonant frequency, shunt impedance and quality factor of a pill-box cavity in a storage ring. [CAVITY]

Keil and Zotter have analyzed the electromagnetic fields excited by the longitudinal density fluctuations of an unbunched relativistic particle beam drifting in a corrugated vacuum chamber of circular cross section. At higher frequencies, these corrugations become resonant cavities. Zotter has written a computer program known as KN7C to compute the resonant frequencies. However, in the actual use of KN7C, some difficulties are encountered. To surmount these difficulties, the program known as CA… more

Date: October 1, 1983

Creator: Aguero, V. M. & Ng, K. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Recent transition crossing results from the Fermilab Main Ring

This paper outlines the known mechanisms for emittance dilution and beam loss during transition crossing. These include scraping, Johnsen`s nonlinear effect, bunch length mismatch, microwave and negative-mass instabilities, and beam loading. A recent experiment on transition crossing performed with 13 proton bunches injected into the Main Ring is discussed.

Date: March 1, 1997

Creator: Bhat, C. M. & Ng, K. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Estimate of the contributions of bellows to the impedances and beam instabilities of the SSC

Between sections of the vacuum chamber, bellows are needed to compensate for thermal expansion and transverse offsets. For beampipe made of stainless steel with a coefficient of linear expansion 19 x 10/sup -6///sup 0/C and a temperature variation of approx.316/sup 0/C, the allowance for bellows is approx.1.2% of the total length of the beampipe, if we assume that the bellows are 50% compressible. This implies 1.08 km of bellows for Design A of the SSC which has a circumference of 90 km. Such a… more

Date: July 1, 1985

Creator: Bisognano, J. & Ng, K. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Coherent betatron instability in the Tevatron

The coherent betatron instability was first observed during the recent 1987-88 Tevatron fixed target run. In this operating mode 1000 consecutive bunches are loaded into the machine at 150 GeV with a bunch spacing of 18.8 /times/ 10/sup -9/ sec (53 MHz). The normalized transverse emittance is typically 15 ..pi.. /times/ 10/sup -6/ m rad in each plane with a longitudinal emittance of about 1.5 eV-sec. The beam is accelerated to 800 GeV in 13 sec. and then it is resonantly extracted during a 23 s… more

Date: June 9, 1988

Creator: Bogacz, S. A.; Harrison, M. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Impedance calculation for ferrite inserts

Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwav… more

Date: January 1, 2005

Creator: Breitzmann, S. C.; Lee, S. Y. & Ng, K. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Design of a {gamma}{sub t}-jump system for Fermilab Main Injector

In order to control the beam emittance and reduce the particle losses during the transition crossing at high intensity, a conceptual design of a {gamma}{sub t}-jump system for the FNAL Main Injector is presented. It is a first-order system employing local dispersion inserts at existing dispersion free straight sections. The goal is to provide a jump of {Delta}{gamma}{sub t} from +1 to -1 within 0.5 ms. The system consists of 8 sets of pulsed quadrupole triplets. These quads have pole tips of th… more

Date: June 1, 1997

Creator: Chou, W., Brown, B.C., Fang, S., Leibfritz, J., Ng, K.Y., Pfeffer, H., Terechkine, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast beam stacking using rf barriers

Two barrier RF systems were fabricated, tested and installed in the Fermilab Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector, which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology.

Date: June 1, 2007

Creator: Chou, W.; Capista, D.; Griffin, J.; Ng, K.-Y.; Wildman, D. & /Fermilab

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Correction of unevenness in recycler beam profile

A beam confined between two rf barriers in the Fermilab Recycler Ring exhibits very uneven longitudinal profile. This leads to the consequence that the momentum-mined antiproton bunches will have an intolerable variation in bunch intensity. The observed profile unevenness is the result of a tiny amount of rf imperfection and rf beam-loading. The profile unevenness can be flattened by feeding back the uneven rf fan-back gap voltage to the low-level rf.

Date: May 1, 2006

Creator: Crisp, J.; Hu, M. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Muon Muon Collider: Feasibility Study

A feasibility study is presented of a 2 + 2 TeV muon collider with a luminosity of L = 10{sup 35} cm{sup -2}s{sup -1}. The resulting design is not optimized for performance, and certainly not for cost; however, it does suffice - we believe - to allow us to make a credible case, that a muon collider is a serious possibility for particle physics and, therefore, worthy of R and D support so that the reality of, and interest in, a muon collider can be better assayed. The goal of this support would … more

Date: April 5, 2012

Creator: Gallardo, J. C.; Palmer, R. B.; Tollestrup, A. V.; Sessler, A. M.; Skrinsky, A. N.; Geer, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dancing bunches at Tevatron

No Description Available.

Date: July 2, 2003

Creator: Guo, W.; Moore, R.; Ng, K. Y. & Lee, S. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Study of collective effect in ionization cooling

As a charged particle passes through a non-gaseous medium, it polarizes the medium and induces wake fields behind it. Same thing happens in ionization cooling. The interaction with wake fields perturbs the stopping power of beam particles. The perturbation strongly depends on the densities of both the incident beam and the medium. To understand this collective effect, detailed studies have been carried out. Both analytic and simulation results are obtained and compared.

Date: September 1, 2009

Creator: Huang, D.; Ng, K. Y. & Roberts, T. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Transition crossing in the Fermilab Main Ring, past and present

A recent installation of passive mode dampers in the Booster has eliminated most of the longitudinal emittance blowup of intense bunches due to coupled-bunch instabilities. As a result, high intensity effects (negative-mass instability) dominate the present transition crossing in the Main Ring for the high-intensity cycles. A negative-mass stability limit is derived for transition crossing in the Main Ring and recent observations of high frequency signals around transition is presented. Finally… more

Date: May 1, 1993

Creator: Kourbanis, I. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transition crossing in the Fermilab Main Ring, past and present

Date: May 1, 1993

Creator: Kourbanis, I. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Beam impedances of position monitors, bellows, and abort kicker

The miscellaneous components of an accelerator may contribute a substantial or even dominant part of the interaction between beam and surroundings. We have estimated the beam impedances of a few of these components. When needed, we have added our own conceptions to the descriptions available at the Workshop on the RHIC Performance in order to make definite the calculations of impedance. These assumed parameters, while not unique, hopefully illustrate feasible and typical designs. 8 refs., 4 fig… more

Date: May 1, 1988

Creator: Lambertson, G. R. & Ng, K.-Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Application of a localized chaos by rf-phase modulations in phase-space dilution

Physics of chaos in a localized phase-space region is exploited to produce a longitudinally uniformly distributed beam. Theoretical study and simulations are used to study its origin and applicability in phase-space dilution of beam bunch. Through phase modulation to a double-rf system, a central region of localized chaos bounded by invariant tori are generated by overlapping parametric resonances. Condition and stability of the chaos will be analyzed. Applications include high-power beam, beam… more

Date: October 1, 2010

Creator: Lee, S. Y. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

On Scaling Properties of Third-Order Resonance Crossing in Particle Accelerator

No Description Available.

Date: October 1, 2012

Creator: Lee, S. Y. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A design of a quasi-isochronous storage ring

Isochronous electron storage rings may offer advantages for future high luminosity meson factories. A Quasi-isochronous lattice based on the design principle of flexible {gamma}{tau} lattice is studied. The emittance and chromatic properties of such a lattice are studied. Applications of this design techniques for electron storage rings will be discussed.

Date: July 1, 1993

Creator: Lee, S. Y.; Ng, K. Y. & Trbojevic, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

On scaling properties of crossing the third-order resonance in particle accelerator

We study effects of charged particle beams crossing a third-order resonance in an accelerator. The distortion of invariant torus during the resonance crossing is used to set 20% emittance growth or 2.5% of trap fraction as the critical resonance strength. We find a simple scaling law for the critical resonance strength vs the tune ramp rate and the initial emittance. The scaling law can be derived by solving Hamilton's equation of motion with stationary phase condition. Such scaling law can be … more

Date: December 1, 2011

Creator: Lee, S. Y.; Pang, X.; Jing, Y.; Luo, T. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron proton two-stream instability at the PSR.

A strong, fast, transverse instability has long been observed at the Los Alamos Proton Storage Ring (PSR) where it is a limiting factor on peak intensity. Most of the available evidence, based on measurements of the unstable proton beam motion, is consistent with an electron-proton two-stream instability. The need for higher beam intensity at PSR [1] and for future high-intensity, proton drivers has motivated a multi-lab collaboration (LANL, ANL, FNAL, LBNL, BNL, ORNL, and PPPL) to coordinate r… more

Date: February 19, 2002

Creator: Macek, R. J.; Browman, A.; Fitzgerald, D.; McCrady, R.; Merrill, F.; Plum, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Impedance and instability threshold estimates in the main injector I

One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and… more

Date: March 1, 1994

Creator: Martens, M. A. & Ng, K. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Impedance budget and beam stability analysis of the Fermilab Main Injector

The impedance budget of the Fermilab Main Injector (MI) is estimated, which includes the contributions from the resistive walls, bellows, rf cavities, steps, Lambertsons, etc. Beam stability during ramping and bunch coalescence is analyzed. The transverse resistive-wall coupled bunch growth is found to be somewhat worse than the situation in the Main Ring (MR).

Date: May 1, 1993

Creator: Martens, M. A. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Impedance budget and beam stability analysis of the Fermilab Main Injector

Date: May 1, 1993

Creator: Martens, M. A. & Ng, K. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Longitudinal Bunch Dynamics in the Tevatron

The authors present their observations of the longitudinal bunch dynamics in Tevatron for uncoalesced proton bunches at 150 GeV and coalesced proton bunches at 150 GeV and 980 GeV. They have observed long-term (> 15 minutes) coherent oscillations of uncoalesced protons that preserve already existing oscillations from upstream accelerators. A single-bunch instability in large intensity protons bunches at 980 GeV has also been observed.

Date: June 2, 2003

Creator: Moore, R.; Balbekov, V.; Jansson, A.; Lebedev, V.; Ng, K. Y. & Shiltsev, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Exploration of ion-antiproton instabilities in the Recycler Ring

Instabilities driven by ions (or electrons) trapped within the space charge potential of a circulating beam are common in accelerators and storage rings. In the recycler, the stored antiproton ({bar p}) beam could trap positive ions (H{sub 2}{sup +}, CO{sup +}, etc.). Conditions for trapping are discussed, and trapping potentials are calculated. Ion trapping can be reduced by clearing electrodes, a beam-free gap (or gaps), and beam shaking. Tune shifts, coherent instabilities and other effects … more

Date: August 4, 2004

Creator: Neuffer, David V.

Item Type: Report

Partner: UNT Libraries Government Documents Department