• M. Ruf, L. Schmidt
  U. Erlangen-Nurnberg LHFT, Erlangen
• S. Setzer
  Siemens Med, Erlangen

For beam position monitoring purposes, particle-in-cell simulations were applied to investigate pickup button and electron beam spectrum characteristics. Results on this simulative approach are presented. Particularly, a comparison is made between simulation results from the PIC solver of CST’s PARTICLE STUDIO and experimental data gathered with a 6 MeV electron beam from a linear accelerator for medical purposes. The measurements were conducted under non-vacuum conditions. Good agreement between simulation and experimental data was achieved although non-negligible electron spread during air passage of the electron beam can be assumed.

• M. Putignano, K.-U. Kühnel
  MPI-K, Heidelberg
• M. Putignano, C.P. Welsch
  The University of Liverpool, Liverpool

Growing interest in the development of low energy projectile beams, in particular heavy ions and antiprotons, calls for new beam instrumentation to be developed to match the strict requirements on ultra-high vacuum and low beam perturbation. When it comes to transverse profile monitoring, a convenient solution for simultaneous determination of both transverse profiles is found in a neutral supersonic gas-jet target shaped into a thin curtain and the two-dimensional imaging of the gas ions created by impacting projectiles. The resolution and vacuum efficiency of this monitor is directly linked to the characteristics of the gas-jet curtain. In this contribution we describe the design of a nozzle-skimmer system to be used for the creation of the jet curtain in the first prototype of such a monitor. Using numerical fluid dynamics simulations, we present the effects resulting directly from changes in the geometry of the nozzle-skimmer system on the characteristics of the jet curtain.

• C. Böhme
  UniDo/IBS, Dortmund
• J.L. Conradie
  iThemba LABS, Somerset West
• J. Dietrich, V. Kamerdzhiev
  FZJ, Jülich
• T. Weis
  DELTA, Dortmund

Scintillation is one of the outcomes of beam interaction with residual gas. This process is utilized for non-destructive beam profile monitoring. Test bench measurements at various gas compositions and pressures as well as ones with the circulating proton beam at COSY-Juelich were performed. This was done using a single large photocathode PMT to estimate the photon yield. A multichannel photomultiplier was used along with a lens system to monitor the ion beam profile. Experimental results are presented and the challenges of the approach are discussed.

• J. Egberts, S.T. Artikova
  MPI-K, Heidelberg
• C.P. Welsch
  The University of Liverpool, Liverpool

The majority of particles in a beam are located close to the beam axis, called the beam core. However, particles in the tail distribution of the transverse beam profile can never be completely avoided and are commonly referred to as beam halo. The light originating from or generated by the particle beam is often used for non- or least destructive beam profile measurements. Synchrotron radiation, optical transition, or diffraction radiation are examples of such measurements. The huge difference in particle density between the beam core and its halo, and therefore the huge intensity ratio of the emitted light is a major challenge in beam halo monitoring. In this contribution, results from test measurements using a flexible core masking technique are presented indicating way to overcome present limitations. This technique is well-known in e.g. astronomy, but since particle beams are not of constant shape in contrast to astronomical objects, a quickly adjustable mask generation process is required. The flexible core masking technique presented in this paper uses aμmirror array to generate a mask based on an automated algorithm.

• S. Jackson, B. Dehning, J. Emery, J. Fitzek, F. Follin, V. Kain, G. Kruk, M. Misiowiec, C. Roderick, M. Sapinski, C. Zamantzas
  CERN, Geneva

The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. As well as protecting the machine, the system is also used as a means of diagnosing machine faults, and providing feedback of losses to the control room and several systems such as the Collimation, the Beam Dump and the Post-Mortem. The system has to transmit and process signals from over 4'000 monitors, and has approaching 3 million configurable parameters. This paper describes the types of configuration data needed, the means used to store and deploy all the parameters in such a distributed system and how operators are able to alter the operating parameters of the system, particularly with regard to the loss threshold values. The various security mechanisms put in place, both at the hardware and software level, to avoid accidental or malicious modification of these BLM parameters are also shown for each case.

• G.G. Venturini, B. Dehning, E. Effinger, C. Zamantzas
  CERN, Geneva

A novel radiation hardened current digitizer ASIC is in planning stage, aimed at the acquisition of the current signal from the ionization chambers employed in the Beam Loss Monitoring system in CERN accelerator chain. The purpose is to match and exceed the performances of the existing discrete component design, currently in operation in the Large Hadron Collider (LHC). The specifications include: a dynamic range of nine decades, defaulting to the 1pA-1mA range but adjustable by the user, ability to withstand a total integrated dose of at least 10 kGray in 20 years of operation and user selectable integrating windows, as low as 500ns. Moreover, the integrated circuit can be employed to digitize currents of both polarity with a minimum number of external components and without needing any configuration. The target technology is IBM 130 nm CMOS process. The specifications, the architecture choices and the reasons on which they're based upon are discussed in the paper.

• G.G. Venturini, B. Dehning, E. Effinger, J. Emery, C. Zamantzas
  CERN, Geneva

A discrete components design of a current digitizer based on the current-to-frequency converter (CFC) principle is currently under development at CERN. The design targets at rather high input current compared to similar designs, with a maximum equal to 200mA and a minimum of 1nA, as required by the ionization chamber that will be employed in the Proton Synchrotron and Booster accelerators as well as in the LINAC. It allows the acquisition of currents of both polarities without requiring any configuration and provides fractional counts through an ADC to increase the resolution. Several architectural choices are being considered for the front-end circuit, including charge balance integrators, dual-integrator input stages, integrators with switchable-capacitor, in both synchronous and asynchronous versions. The signal is processed by an FPGA and transmitted over a VME64x bus. Design, simulations and measurements are discussed in this article.

• J. Harasimowicz
  Cockcroft Institute, Warrington, Cheshire
• J. Harasimowicz, C.P. Welsch
  The University of Liverpool, Liverpool

The Ultra-low energy Storage Ring (USR) at the future Facility for Low-energy Antiproton and Ion Research (FLAIR) at GSI, Germany will decelerate antiproton beams of very low intensities from 300 keV down to 20 keV. Such beams can be easily disturbed by standard monitoring devices and the development of new sensitive diagnostic techniques is required. To overcome the limitations related to a very low number of particles, a low signal-to-noise ratio and ultra-low kinetic energies, a resonant capacitive pick-up has been proposed as a beam position monitor. In the planned solution, the signal gain will be realised by the use of a specially designed resonant circuit optimized to meet the requirements of the USR. The current overall design studies of the resonant capacitive pick-up, including simulations of the beam displacement sensitivity and linearity for different pick-up geometries and the equivalent resonant circuit optimisation, will be discussed.

• P.S. Yoon, D.P. Siddons
  BNL, Upton, Long Island, New York

We have developed a photodiode-based X-ray beam-position monitor with high-spatial resolution for use on the future beamlines at NSLS-II. A ring array of 32 Si PIN photodiodes were fabricated for a photon sensor, and a newly-designed HERMES4 ASIC die was integrated into the data-acquisition system. A series of precision measurements for electrical characterization of the Si-photodiode sensor and the ASIC die demonstrated that the inherent noise is sufficiently below tolerance levels. Following up with a series of modeling efforts including geometrical optimization, we have built prototype detectors. In this paper, we present the development of the new state-of-the-art X-ray BPM and experimental measurements performed on the existing X12A beamline at NSLS.

• J.J. García-Garrigós, C. Blanch Gutierrez, J.V. Civera-Navarrete, A. Faus-Golfe
  IFIC, Valencia

A set of two Inductive Pick-Up (IPU) prototypes with its associated electronics for Beam Position Monitoring (BPM) in the Test Beam Line (TBL) of the 3rd Compact Linear Collider (CLIC) Test Facility (CTF3) at CERN were designed, constructed, and tested by the IFIC team. One prototype and two units of the series production are already installed in the TBL line. In the first part of the paper we describe the characterization tests of these two prototypes carried out at CERN, and the first beam tests performed to one of them. The second part of this paper is dedicated to the description of the issues addressed by the start of the series production and the characterization tests of the first series units performed with a custom-made low-frequency wire setup. This setup which emulates the beam position variation allows to carry out the series tests in an automatized manner and with higher accuracy.