ERL2015 - List of Authors (Dunham, B.M.)

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MOPBTH005

A FFAG-ERL at Cornell, a BNL/Cornell Collaboration

G.H. Hoffstaetter, I.V. Bazarov, J. Dobbins, B.M. Dunham, C.E. Mayes, J.R. Patterson, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I. Ben-Zvi, J.S. Berg, M. Blaskiewicz, S.J. Brooks, K.A. Brown, W. Fischer, Y. Hao, W. Meng, F. Méot, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Cornell University has prototyped technology essential for any high-brightness electron ERL. This includes a DC gun and an SRF injector Linac, a high-current CW cryomodule, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. All these are now available to equip a one-cryomodule ERL, and laboratory space has been cleared out and is radiation shielded to install this ERL at Cornell. BNL has designed a multi-turn ERL for eRHIC where beam is transported 22 times around the RHIC tunnel. The number of transport lines is minimized by using two non-scaling FFAG arcs. A collaboration between BNL and Cornell has been formed to investigate the new NS-FFAG optics of this design, built with permanent magnets, and to commission the unprecedented multi-turn ERL operation. This collaboration plans to install a NS-FFAG return loop and the associated optics-matching sections at Cornell’s one-cryomodule ERL. This FFAG-ERL will be installed in several stages, each of which investigates crutial parts of this new design.

Slides MOPBTH005 [14.410 MB]

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MOPCTH008

Cornell Injector Performance

A.C. Bartnik, I.V. Bazarov, L. Cultrera, B.M. Dunham, C.M. Gulliford, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported, in part, by the LCLS-II Project and the U.S. Department of Energy, contract No. DE-AC02-76SF00515 and DE-SC0012493.
We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (>100 pC) beams produced in the dc gun-based Cornell photoinjector. In particular, we show that the cathode thermal emittance dominates the final emittance at charges up to 300 pC. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances.

Slides MOPCTH008 [4.267 MB]

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WEICLH1059

An Inverse Compton Scattering Beamline for High-Energy, Time-Resolved X-Ray Scattering Studies of Materials

J.D. Brock, B.M. Dunham, G.H. Hoffstaetter, V.O. Kostroun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

If constructed, the Energy Recovery Linac (ERL) based on a Fixed Field Alternating Gradient (FFAG) lattice proposed by Cornell University and Brookhaven National Laboratory would provide a unique opportunity to implement a variant of the MIT inverse Compton source concept.* Such a source could deliver an intense (6x10¹⁴ ph/sec), high repetition-rate (100MHz) beam of short pulses (0.05 – 2 ps) of hard x-rays (155 keV) with 1% bandwidth. We will review the generic design, major technical choices, and some potential scientific applications of such a x-ray facility.
*W. S. Graves, W. Brown, F. X. Kaertner, and D. E. Moncton, "MIT inverse Compton source concept," Nuclear Instruments and Methods in Physics Research Section A 608 (1, Supplement 1), S103-S105 (2009).

Slides WEICLH1059 [1.401 MB]

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THIALH2070

A Fast Rotating Wire Scanner for Use in High Intensity Accelerators

T.P. Moore, N.I. Agladze, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, S.J. Full, Y. Li, X. Liu, J.J. Savino, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the financial assistance from the National Science Foundation (Grant No. DMR-0807731).
We have developed a cost-effective, fast rotating wire scanner for use in accelerators where high beam currents would otherwise melt even carbon wires. This new design uses a simple planetary gear setup to rotate a tungsten or carbon wire, fixed at one end, through the beam at speeds in excess of 20 m/s. We present results from bench tests, as well as transverse beam profile measurements taken at Cornell’s high-brightness ERL photoinjector, for beam currents up to 35 mA.

Slides THIALH2070 [1.429 MB]

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THIALH2071

Detection and Clearing of Trapped Ions in the High Current Cornell Photoinjector

S.J. Full, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: DOE Nuclear Physics award DE-SC0012493
We evaluate the effectiveness of three ion-clearing strategies in the Cornell high intensity photoinjector: DC clearing electrodes, bunch gaps, and beam shaking. We present data from recent experiments where we directly measured the residual trapped ion density while employing these clearing methods. Several theoretical models have been developed to estimate the ion creation and clearing rates. The data is well explained by two independent simulation codes that track the motion of ions trapped in the electric field generated by the beam.

Slides THIALH2071 [4.104 MB]

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