CLIC Wake Field Monitor as a detuned Cavity Beam Position Monitor: Explanation of center offset between TE and TM channels in the TD26 structure

The Wake Field Monitor (WFM) system installed on the CLIC prototype accelerating structure in CERN Linear Accelerator for Research (CLEAR) has two channels for each horizontal/vertical plane, operating at different frequencies. When moving the beam relative to the aperture of the structure, a disagreement is observed between the center position of the structure as measured with the two channels in each plane. This is a challenge for the planned use of WFMs in the Compact Linear Collider (CLIC), where they will be used to measure the center offset between the accelerating structures and the beam. Through a mixture of simulations and measurements, we have discovered a potential mechanism for this, which is discussed along with implications for improving position resolution near the structure center, and the possibility determination of the sign of the beam offset.Comment: 16 pages, 20 figure

A Method for Determining the Roll Angle of the CLIC Accelerating Structures From the Beam Shape Downstream of the Structure

International audienceThe Compact Linear Collider (CLIC) accelerating structures have a four-fold symmetry from the radial waveguides for damping higher order modes. This symmetry allows for an octupole component of the rf fields to co-propagate with the main accelerating field. The effect of this octupole mode has been observed at the CLIC test facility 3. In CLIC the accelerating structures are mounted together on a moveable girders. There are four vertical and four horizontal actuators on the girder, which allows for 5D control in a limited range and for instance we can roll the girder. By observing the beam shape perturbed by the octupole field on a screen downstream from the structure we can determine the roll angle and thus align the structure azimuthally. Here we discuss a possible method and show some preliminary results

Beam Tests at the CLIC Test Facility, CTF3

The CLIC Test Facility CTF3 has been built at CERN by the Compact Linear Collider (CLIC) International Collaboration, in order to prove the main feasibility issues of the two-beam acceleration technology on which the collider is based. After the successful completion of its initial task, CTF3 is continuing its experimental program in order to give further indications on cost and performance issues, to act as a test bed for the CLIC technology, and to conduct beam experiments aimed at mitigating technological risks. In this paper we discuss the status of the ongoing experiments and present the more recent results, including improvements in beam quality and stability

Development of the AWAKE Stripline BPM Electronics

The stripline BPMs of AWAKE (The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN) are required to measure the position of the single electron bunch with a resolution of 10 um rms, for the bunch charge of 100 pC to 1 nC. This paper presents a AFE-Digital processing system developed at TRIUMF (Canada) which achieved such performance. The design of the electronics readout system is reviewed. The beam test results at CALIFES of CERN are also described

VHEE High Dose Rate Dosimetry Studies in CLEAR

International audienceThe 200 MeV electron beam of the CERN Linear Accelerator for Research (CLEAR) user facility at CERN has been intensively used to study the potential use of Very High Energy Electrons (VHEE) in cancer radiotherapy. In particular, irradiation tests have been performed in the high dose rate regime, which has gained a lot of interest for the so called FLASH biological effect, in which cancer cells are damaged while healthy tissue is largely spared. High dose rate dosimetry, though, poses a number of challenges: to validate standard or new methods of passive dosimetry, like radiochromic films and alanine pellets, and especially to develop new methods for real-time dosimetry since the normally used ionization chambers suffer from non-linear effects at high dose rates. In this paper we describe the results of experimental activities at CLEAR aimed at developing solid, high-dose rate dosimetry standards adapted to VHEE beams

Beam-Based Alignment Studies at CTF3 Using the Octupole Component of CLIC Accelerating Structures

International audienceThe Compact Linear Collider (CLIC) uses normal-conducting accelerating structures that are sensitive to wakefield effects and therefore their alignment is extremely important. Due to the four-fold symmetry of the structures, they allow for an octupole component of the rf fields. By scanning the beam transversely we can determine the center of the structures from the shifts in beam position due to the kicks from the octupole field. We present some initial results from measurements at the CLIC test facility 3 at CERN

Status of VHEE Radiotherapy Related Studies at the CLEAR User Facility at CERN

International audienceDespite the increase in interest in using Very High Energy Electron (VHEE) beams for cancer radiotherapy many unanswered questions in its development remain. The use of test facilities will be an essential tool used to solve these issues. The 200 MeV electron beam from the CERN Linear Accelerator for Research (CLEAR) has been used extensively, in collaboration with several research institutes, to perform dosimetry studies and explore potential applications of VHEE beams to radiotherapy, including the exploitation of the so called FLASH effect. In this paper, we present an overview of past studies with emphasis on the more recent results. We describe methods, techniques and equipment developed at CERN in this framework, and give an outlook on future activities

Methods for VHEE/FLASH Radiotherapy Studies and High Dose Rate Dosimetry at the CLEAR User Facility

The CERN Linear Electron Accelerator for Research (CLEAR), operating since 2017, is a user facility providing electron beams for a varied and large range of experiments. The accelerator can generate a 60-220 MeV electron beam and it was recently selected to study the feasibility of using Very High Energy Electrons (VHEE) at Ultra High Dose Rate (UHDR) for cancer radiotherapy. One of the studies in CLEAR is to study the impact of sending the total dose in a short amount of time (also called UHDR) and study the FLASH biological effect in which deep-seated cancer cells are damaged while the healthy tissues are spared. The dosimetry in CLEAR is measured using both passive dosimetry with radiochromic films or radio-photo-luminescent dosimeters. In this paper different methods for dosimetry studies and experiments in which they are used will be presented