As part of CERN's medical application research, a compact electrode system (< 30 cm) has been designed to facilitate low-current, multiparticle beam extraction and matching to a high-frequency RFQ. This study explores the innovative extraction system design and evaluates its simulation performance. Superfish (SF) and CST Studio Suite were employed to export the 2D and 3D electric field maps of the extraction system for beam dynamics simulations. Beam dynamics simula-tions using the Travel code have confirmed the sys-tem's ability to deliver a high-quality, low-current par-ticle beam fully matched to a 750 MHz RFQ, capable of accelerating particles with a 𝑞/𝑚 ratio of ½ to 1. This paper provides an overview of the key design considerations, geometry layout, and beam dynamics results.

As part of CERN's medical application research, a compact electrode system (< 30 cm) has been designed to facilitate low-current, multiparticle beam extraction and matching to a high-frequency RFQ. This study explores the innovative extraction system design and evaluates its simulation performance. Superfish (SF) and CST Studio Suite were employed to export the 2D and 3D electric field maps of the extraction system for beam dynamics simulations. Beam dynamics simula-tions using the Travel code have confirmed the sys-tem's ability to deliver a high-quality, low-current par-ticle beam fully matched to a 750 MHz RFQ, capable of accelerating particles with a 𝑞/𝑚 ratio of ½ to 1. This paper provides an overview of the key design considerations, geometry layout, and beam dynamics results.

Interest in helium ions for cancer therapy is growing, motivated by their superior conformability as compared to protons or carbon. Clinical trials are starting, using beams produced by large carbon synchrotrons. To exploit the potential of this new ion, a compact synchrotron is being designed to accelerate helium and protons at treatment energies, for about half the size of a carbon machine. The helium LINAC is designed to operate at higher duty cycle than required for synchrotron injection. Beam pulses can be sent to a target producing radioisotopes, in particular alpha emitters to be used for targeted alpha therapy of cancer. The 352 MHz LINAC is made of 3 sections. To increase the efficiency with respect to a standard Drift Tube LINAC (DTL), the first section from 1 to 5 MeV/u is made of a Quasi-Alvarez DTL, a structure combining high efficiency and smooth beam optics. Only this section is powered when injecting helium ions into the synchrotron. The second and third sections of DTL type have energies of 7 MeV/u, the threshold for production of 211At, the most widely used alpha emitter, and 10 MeV/u, for injection of protons and production of other radioisotopes.

The project Anthem, funded within the Next Generation EU initiatives, foresees the realization of an innovative accelerator based BNCT (Boron Neutron Capture Therapy) facility at Caserta, Italy. The INFN (LNL, Pavia, Napoli, Torino) has in charge the design and construction of the epithermal neutron source, that will assure a flux of 10^9 n/(s cm2) with characteristics suited for deep tumors treatment. The driver is a cw RFQ, able to produce proton beam of 30 mA 5 mA. impinging on a beryllium target. Specific challenges are related to the medical application of the device. In the paper an overview of the project will be given.

The tumor therapy facility HIT, Heidelberg, Germany is in operation with light ion beams up to carbon since 2009. The 7 A MeV, 216.8 MHz synchrotron injector linac with a total length of 5 m is designed for the ion C^(4+) from an ECR ion source. The RFQ accelerates the beam from 8 A keV up to 400 A keV and is at present a bottleneck in beam transmission. After a careful analysis of the beam quality along the RFQ it was decided by HIT to order a new RFQ from Bevatech with higher beam acceptance and with tight mechanical tolerances. Other features are optimized entrance and exit gaps by including longitudinal field components, which are characteristic for 4-Rod-RFQs. A complete dipole field compensation along the mini-vane electrodes is another improvement. This RFQ is scheduled to replace the old one in 2026.

The project Anthem, funded within the Next Generation EU initiatives, foresees the realization of an innovative accelerator based BNCT (Boron Neutron Capture Therapy) facility at Caserta, Italy. The INFN (LNL, Pavia, Napoli, Torino) has in charge the design and construction of the epithermal neutron source, that will assure a flux of 10^9 n/(s cm2) with characteristics suited for deep tumors treatment. The driver is a cw RFQ, able to produce proton beam of 30 mA 5 mA. impinging on a beryllium target. Specific challenges are related to the medical application of the device. In the paper an overview of the project will be given.

Present status and future prospects of the iBNCT accelerator will be discussed. Several accelerator-based neutron sources for Boron Neutron Capture Therapy (BNCT) have been developed in the world. The iBNCT (Ibaraki, BNCT) is a linac-based BNCT facility which is operated by University of Tsukuba and KEK in close collaboration with the local government, Ibaraki prefecture. The accelerator is based on the design and experiences of the J-PARC linac, and consists of an ion source, 3-MeV RFQ, 8-MeV DTL and a Beryllium target with modulators. The project aims to realize a compact and low activation BNCT accelerator of several mA proton beam with high duty factor to obtain the thermal neutron flux required for BNCT, but with high stability as a medical accelerator. Originally the cavities were designed with the minimum amount of cooling water, and their resonance frequencies were maintained by dynamical control of the water temperature according to the RF power input. However, after the interlock due to RFQ discharge, the resonance frequency was shifted frequently. By improving and enhancing the cooling water and vacuum, stable operation at an average current of 2 mA has been achieved. We are performing the pre-clinical testing in FY2022, and prepare to start clinical trials in FY2023. This reports the present status of the iBNCT accelerator and its future prospects.

Given the present availability of high-gradient accelerator technology for compact and cost-effective electron linacs in the 100-200 MeV energy range, the interest for Very High Energy Electron (VHEE) radiotherapy (RT) for cancer treatment recently reached an all-time high. Particular significance is assumed by the Ultra-High Dose Rate (UHDR) regime where the so-called FLASH biological effect takes place, in which cancer cells are damaged while healthy tissue is largely spared. VHEE beams from linacs are especially well adapted for FLASH RT, given their penetration depth and the high beam current needed to treat large deep-seated tumours. In recent years, several multidisciplinary user groups carried out a number of studies on VHEE and FLASH RT issues using the CERN Linear Accelerator for Research (CLEAR) user facility, in close collaboration with the local operation team. In this paper we give an overview of such activities and describe the main results of chemical and biological tests aimed at clarifying the damage mechanisms at the root of the FLASH effect and the relevant beam parameters needed to achieve it. We also describe the dedicated systems and methods developed and used in CLEAR for these activities, focusing on recent advances in the crucial aspects of uniform beam delivery and high dose rate real-time dosimetry.