• J. Yang, L. Cao, T. Hu, D. Li, K.F. Liu, B. Qin, J. Xiong, Y.Q. Xiong, T. Yu
  HUST, Wuhan

Funding: National Natural Science Foundation of China (No. 10435030)

A 10MeV H^- compact cyclotron (CYCHU-10) is under construction in Huazhong University of Science and Technology (HUST). This paper presents a magnetic field measurement system for measuring the cyclotron magnet. A Hall probe and a granite x-y stage are adopted in the project. The Cartesian mapping will replace traditional polar system. The motion control and data acquisition system for the magnetic field measurement consists of a Teslameter and Hall probe, servomotors, a motion control card, optical linear encoder systems and an industrial PC. The magnetic field will be automatically scanned by this apparatus, and a flying mode will be the main running mode to reduce measure time.

• B. Qin, M. Fan, D. Li, K.F. Liu, Y.Q. Xiong, J. Yang, T. Yu, L. Zhao
  HUST, Wuhan

Funding: Work supported by National Nature Science Foundation of China (10435030) and National Science Foundation for Post-doctoral Scientists of China (20080430973)

Low energy compact cyclotrons for short-life isotopes production delivered to the Positron Emission Tomography (PET) facilities have foreseeable prospects with growing demands in medical applications. The Huazhong University of Science and Technology (HUST) proposed to develop a 10MeV PET cyclotron CYCHU-10. The design study of the main magnet and the central region was introduced. A matrix shaping method with the radial fringe field effect and artificial control was adopted to obtain field isochronisms precisely. The central region was optimized to attain 35° RF phase acceptance and low vertical beam loss rate.

• L. Cao, M. Fan, T. Hu, J. Huang, D. Li
  HUST, Wuhan

Funding: Nation Nature Science Foundation of China,10435030

At Huazhong University of Science and Technology (HUST), the design study of a 10 MeV compact cyclotron CYCHU-10 for the application of Positron Emission Tomography (PET) has been developed since 2007. This paper describes the recent status of RF cavities including numerical calculation results of basic parameters, the capacitive trimmer to overcome frequency shift when in operation and the construction and cold test of the 1:1 scale prototype. The inductive coupling loop design and matching simulation with the RF power generator are also presented

• D. Li, L. Cao, T. Hu, J. Huang, B. Qin, J. Yang
  HUST, Wuhan

Funding: Work supported by National Nature Science Foundation of China, 10435030

In order to reduce the cost of the signal generator comprising a high performance direct digital synthesizer (DDS), the method of picking up a desired aliased signal of DDS output is adopted in the study. The chip AD9850 is used to synthesize RF signal in the system, and the amplitude modulation of the system is achieved by altering the external connection resistance of the chip. The output frequency is tunable from 99.5 to 101MHz. The principle and the test results of the signal synthesizer will be presented. The amplifier based on tetrode technology can deliver the 10kW RF power in a continuous wave (CW) mode of operation. The driver amplifier consists of two solid-state modules, and it can provide the tetrode with up to 300W input power. The tetrode operates in the grounded cathode configuration. The conceptual design of the final stage amplifier will also be demonstrated in this paper.

• T. Hu, L. Cao, J. Huang, D. Li, B. Qin, J. Yang, T. Yu
  HUST, Wuhan

Funding: Nation Nature Science Foundation of China,10435030

The design study of Cyclotron CYCHU 10MeV has been developed at Huazhong University of Science and Technology (HUST). Because of the low center frequency (100MHz) of it’s RF system, we should choose suitable directional couplers for the RF system which is supposed to be high-directivity and tight-structure. This paper analyses and synthesizes kinds of directional couplers, espacially microstrip structure, for it’s tinier volume at the low center frequency compared with stripline and branch structures. The achievement of the high-directivity with microstrip configuration is carried out by the distributed capacitor to decrease the even and odd mode phase difference. Capacitive compensation is performed by the interdigital capacitors. The proposed structure is easy to fabricate and incorporate another microwave device due to planner microstrip.

• M.A. Green, D. Li, S.P. Virostek, M.S. Zisman
  LBNL, Berkeley, California
• A.B. Chen, X.L. Guo, X.K. Liu, H. Pan, L. Wang, H. Wu, F.Y. Xu, S.X. Zheng
  ICST, Harbin
• D.J. Summers
  UMiss, University, Mississippi

Funding: This work is supported by funds under the “985-2” plan of HIT. This work is also supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231 and by NSF through NSF-MRI-0722656.

The superconducting coupling solenoid for MuCOOL and MICE will have an inside radius of 750 mm, and a coil length of 285 mm. The MuCOOL coupling coil is identical to the MICE coupling coils. The MICE coupling magnet will have a self inductance of 592 H. When operated at it maximum design current of 210 A (the highest momentum operation of MICE), the magnet stored energy will be about 13 MJ. These magnets will be kept cold using a pair of pulse tube cryocoolers that deliver 1.5 W at 4.2 K and 55 W at 60 K. This report describes the progress on the MuCOOL and MICE coupling magnet design and engineering. The progress on the construction of the first coupling coil will also be presented.

• S.P. Virostek, M.A. Green, D. Li, M.S. Zisman
  LBNL, Berkeley, California

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.

The Muon Ionization Cooling Experiment (MICE) is an international collaboration that will demonstrate ionization cooling in a section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. At each end of the cooling channel a spectrometer solenoid magnet consisting of five superconducting coils will provide a 4 tesla uniform field region. The scintillating fiber tracker within the magnet bore tubes will measure the emittance of the muon beam as it enters and exits the cooling channel. The 400 mm diameter warm bore, 3 meter long magnets incorporate a cold mass consisting of two coil sections wound on a single aluminum mandrel: a three-coil spectrometer magnet and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The fabrication of the spectrometer solenoids has been completed, and preliminary testing and field mapping of the magnets is nearly complete. The key design features of the spectrometer solenoid magnets are presented along with a summary of the progress on the testing and magnetic measurements.

• F. Sannibale, K.M. Baptiste, J.N. Corlett, T.M. Huang, S. Kwiatkowski, D. Li, J. Qiang, J.W. Staples, R.P. Wells, L. Yang, A. Zholents
  LBNL, Berkeley, California
• J.W. McKenzie
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231

A high-brightness high-repetition rate photo-injector based on a normal conducting 187 MHz RF cavity design capable of CW operation is under construction at the Lawrence Berkeley National Laboratory. A cathode field of ~20 MV/m accelerates electron bunches to 750 keV with peak current, energy spread and transverse emittance suitable for FEL and ERL applications. A vacuum load-lock mechanism is included and a 10 picoTorr range vacuum capability allows most types of photocathodes to operate at a MHz repetition rate with present laser technology. The status of the project is presented.

• D. Huang, Y. Torun
  IIT, Chicago, Illinois
• A.D. Bross, A. Moretti, Z. Qian
  Fermilab, Batavia
• D. Li, M.S. Zisman
  LBNL, Berkeley, California
• J. Norem
  ANL, Argonne

Funding: The United States Department of Energy

The accelerating gradient in a RF cavity is limited by many factors such as the surface material properties, RF frequency, the external magnetic field and the gas pressure inside the cavity. In the MuCool Program, RF cavities are studied with the aim of understanding these basic mechanisms and improving their maximum stable accelerating gradient. These cavities are being developed for muon ionization cooling channel for a Neutrino Factory or Muon Collider. We report studies using the 805 MHz and 201 MHz RF cavities in the MuCool Test Area (MTA) at Fermilab. New results include data from buttons of different materials mounted in the 805 MHz cavity, study of the accelerating gradient in the 201 MHz cavity and X-ray background radiation from the cavities due to Bremsstrahlung. The 201 MHz cavity has been shown to be stable at 19 MV/m at zero magnetic field, well in excess of its 16 MV/m design gradient. We will also discuss results from the 201 MHz cavity study in magnetic field and introduce the test of E × B effects with the 805 MHz box cavity.

• D. Li, N. Andresen, A.J. DeMello, S.P. Virostek, M.S. Zisman
  LBNL, Berkeley, California
• R.A. Rimmer
  JLAB, Newport News, Virginia
• D.J. Summers
  UMiss, University, Mississippi

The international muon ionization cooling experiment (MICE) requires low frequency and normal conducting RF cavities to compensate for muon beams’ longitudinal energy lost in the MICE cooling channel. Eight 201-MHz normal conducting RF cavities with conventional beam irises terminate by large and thin beryllium windows are needed. The cavity design is based on a successful prototype cavity for the US MUCOOL program. The MICE RF cavity will be operated at 8-MV/m in a few Tesla magnetic fields with 1-ms pulse length and 1-Hz repetition rate. The cavity design, fabrication, post process plans and as well as integration to the MICE cooling channel will be discussed and presented in details.

• M. BastaniNejad, A.A. Elmustafa
  Old Dominion University, Norfolk, Virginia
• J.M. Byrd, D. Li
  LBNL, Berkeley, California
• M.E. Conde, W. Gai
  ANL, Argonne
• R.P. Johnson, M.L. Neubauer, R. Sah
  Muons, Inc, Batavia
• A. Moretti, M. Popovic, K. Yonehara
  Fermilab, Batavia

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and FRA DOE contract number DE-AC02-07CH11359

Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) and pressure barrier capable of operating both at high pressure and in vacuum been designed and built, and preliminary testing has been completed. A series of detailed experiments is planned at the Argonne Wakefield Accelerator.

• L. Ge, K. Ko, Z. Li, C.-K. Ng
  SLAC, Menlo Park, California
• D. Li
  LBNL, Berkeley, California
• R. B. Palmer
  BNL, Upton, Long Island, New York

Funding: This work was supported by DOE contract No. DE-AC02-76SF00515 NERSC

The muon cooling cavity for Muon Collider works under strong external magnetic fields. It has been observed that this external magnetic field can enhance the multipacting activities and dark current heating. As part of a broad effort to optimize external magnetic field map and cavity shape for minimal dark current and multipacting, we use SLAC’s 3D parallel code Track3P to analyze the multipacting and dark current issues of the design. Track3P has been successfully used to predict multipacting phenomena in cavity and coupler designs. It provides unprecedented capabilities for simulating large-scale accelerator structure systems, including realistic 3D details and low turn-around times. In this paper, we present the comprehensive multipacting and dark current simulations for Muon Collider cavities.

• P.A. McIntosh, R. Bate, C.D. Beard, D.M. Dykes, S.M. Pattalwar
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S.A. Belomestnykh, M. Liepe, H. Padamsee, J. Sears, V.D. Shemelin, V. Veshcherevich
  CLASSE, Ithaca, New York
• A. Büchner, F.G. Gabriel, P. Michel
  FZD, Dresden
• M.A. Cordwell, J. Strachan
  STFC/DL, Daresbury, Warrington, Cheshire
• J.N. Corlett, D. Li, S.M. Lidia
  LBNL, Berkeley, California
• T. Kimura, T.I. Smith
  Stanford University, Stanford, California
• D. Proch, J.K. Sekutowicz
  DESY, Hamburg
• A. Quigley
  STFC/DL/SRD, Daresbury, Warrington, Cheshire

The collaborative development of an optimised cavity/cryomodule solution for application on ERL facilities, has now progressed to final assembly and testing of the cavity string components and their subsequent cryomodule integration. This paper outlines the verification of the various cryomodule sub-components and details the processes utilised for final cavity string integration. The paper also describes the modifications needed to facilitate this new cryomodule installation and ultimate operation on the ALICE facility at Daresbury Laboratory.

• J. Shi, H. Chen, Q. Du, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan
  TUB, Beijing
• D. Li
  LBNL, Berkeley, California

Funding: Supported by National Natural Science Foundation of China (No.10775080)

An S-band RF deflecting cavity has been developed and applied for measuring the bunch length at Tsinghua Thomson-Scattering X-ray Source (TTX). This paper briefly introduces the 3-cell pi-mode standing-wave deflecting cavity and reports the recent experiments of the beam diagnostics for the photo-cathode RF gun, which produces electron bunches with RMS length around 1-ps. It is also observed that the bunches are lengthened while the total charge increases, showing the strong space charge effect at a low beam energy.