FULL TEMPORAL RECONSTRUCTION USING AN ADVANCED LONGITUDINAL DIAGNOSTIC AT THE SPARC FEL

FULL TEMPORAL RECONSTRUCTION USING AN ADVANCED LONGITUDINAL DIAGNOSTIC AT THE SPARC FE

The TOP-IMPLART high-energy protron beam delivery line: a comparison of SRIM, FLUKA, and Fermi-Eyges theory predicions

Nell'ambito del progetto TOP-IMPLART, è stata progettata ed è in fase di “commissioning” una linea di rilascio del fascio per l'acceleratore lineare di protoni TOP-IMPLART dedicata a irraggiamenti a scansione di bersagli estesi a energie di 63 e 71 MeV. Per pianificare adeguatamente tali irraggiamenti, è necessario conoscere la dimensione laterale e la dispersione angolare del fascio che arriva sul piano del bersaglio. In una fase preliminare questa valutazione può essere eseguita utilizzando simulazioni e modelli teorici. In questo Rapporto Tecnico, esaminiamo il progetto attuale della linea di trasporto del fascio TOP-IMPLART utilizzando due codici Monte Carlo, SRIM e FLUKA, nonché un approccio numerico basato sulla teoria di Fermi-Eyges. I risultati mostrano che SRIM sottostima la dimensione laterale e la dispersione angolare del fascio sul piano del bersaglio rispetto a FLUKA. Un test sperimentale conferma che SRIM sottostima la dimensione del fascio, mentre FLUKA è in buon accordo con l'esperimento. Le previsioni della teoria di Fermi-Eyges sono più vicine ai risultati forniti da FLUKA.In the framework of the TOP-IMPLART project, a beam delivery line has been designed and is under commissioning for the TOP-IMPLART proton linear accelerator to enable irradiation scans of extended targets at energies of 63 and 71 MeV. To suitably plan these irradiations, it is necessary to know the lateral size and angular spread of the beam arriving at the target plane. In a preliminary stage, this evaluation can be performed using simulations and theoretical models. In this Technical Report, we examine the current design of the TOP-IMPLART beam delivery line using two Monte Carlo codes, SRIM and FLUKA, as well as a numerical approach based on the Fermi-Eyges theory. The results show that SRIM underestimates the beam’s lateral size and angular spread of the beam at the target plane compared to FLUKA. An experimental test confirms that SRIM underestimates the spot size, while FLUKA is in good agreement with the experiment. The predictions of the Fermi-Eyges theory are closer to the results provided by FLUKA

Approximate calculation of backpropagated energy spectrum for a proton beam

In certain experimental setups used for proton irradiations at the TOP-IMPLART linear accelerator at the ENEA Frascati Center, the energy spectrum of the proton beam is measured at the end of a propagation path, which includes transmission through different materials, such as air, windows, slabs, etc. In this paper, we develop and test an approximate mathematical method to calculate the energy spectrum at the accelerator exit from such a measured transmitted spectrum. In the first experimental test application, the spectrum measurement exploits the visible photoluminescence of F 2 and F 3 + color centers generated in lithium fluoride crystals by the interaction of the crystal lattice with protons. In the second test application, a simulated measurement of a propagated energy spectrum along a transport line is considered. In principle, the proposed method is applicable to the energy spectra of proton beams measured in any manner

Beam commissioning of the 35 MeV section in an intensity modulated proton linear accelerator for proton therapy

This paper presents the experimental results on the Terapia Oncologica con Protoni-Intensity Modulated Proton Linear Accelerator (TOP-IMPLART) beam that is currently accelerated up to 35 MeV, with a final target of 150 MeV. The TOP-IMPLART project, funded by the Innovation Department of Regione Lazio (Italy), is led by Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) in collaboration with the Italian Institute of Health and the Oncological Hospital Regina Elena-IFO. The accelerator, under construction and test at ENEA-Frascati laboratories, employs a commercial 425 MHz, 7 MeV injector followed by a sequence of 3 GHz accelerating modules consisting of side coupled drift tube linac (SCDTL) structures up to 71 MeV and coupled cavity linac structures for higher energies. The section from 7 to 35 MeV, consisting on four SCDTL modules, is powered by a single 10 MW klystron and has been successfully commissioned. This result demonstrates the feasibility of a “fully linear” proton therapy accelerator operating at a high frequency and paves the way to a new class of machines in the field of cancer treatment

Recombination effects in the ionization chambers dose delivery monitor of the TOP-IMPLART proton beam

The Intensity Modulated Proton Linear Accelerator for Cancer Therapy (TOP-IMPLART) is under development and construction by ENEA in collaboration with the Italian Institute of Health (ISS) and the Oncological Hospital Regina Elena-IFO with financial support of Regione Lazio. Its peculiar time structure (few microseconds pulse width) and very high peak intensity (109 proton/pulse) demand for ad hoc dose delivery monitors (DDM). The TOP-IMPLART DDM is based on ionization gas chambers. One segmented chamber prototype uses Micro Pattern Gaseous Detector technology for the 2-dimensional simultaneous x/y readout; the charge collected from each active segment (strips with pad-like shape) is readout by a dedicated gain-adaptable electronics. Two small, highly sensitive, integral ionization chambers, using the same electronics, complement the 2D chamber for the monitor of the single pulse beam charge, down to 1 pC/pulse. While under development and deployment of its accelerating modular cavities, the linear TOP-IMPLART beam is improved thanks also to the continuous monitoring and characterization by these devices, whose responses are periodically compared to calibrated dosimetric detectors such as real-time active microDiamond sensor, passive Alanine pellets, intrinsically stable integral Faraday Cup. Different calibration campaigns have been recently conducted to measure the recombination and dose-rate effects on the above ionization chambers. The outcome of these measurements shows clear electron-ion recombination in the chamber active volume, largely related to the high beam intensity and its small transverse cross section. Those effects can be taken into account and used to correct the actual measurement of the DDM. In this paper, the TOP-IMPLART project and the DDM devices are shortly presented and details of the above experimental studies are discussed

The Top-Implart Proton Linear Accelerator: Interim Characteristics of the 35 Mev Beam

In the framework of the Italian TOP-IMPLART project (Regione Lazio), ENEA-Frascati, ISS and IFO are developing and constructing the first proton linear accelerator based on an actively scanned beam for tumor radiotherapy with final energy of 150 MeV. An important feature of this accelerator is modularity: an exploitable beam can be delivered at any stage of its construction, which allows for immediate characterization and virtually continuous improvement of its performance. Currently, a sequence of 3 GHz accelerating modules combined with a commercial injector operating at 425 MHz delivers protons up to 35 MeV. Several dosimetry systems were used to obtain preliminary characteristics of the 35-MeV beam in terms of stability and homogeneity. Short-term stability and homogeneity better than 3% and 2.6%, respectively, were demonstrated; for stability an improvement with respect to the respective value obtained for the previous 27 MeV beam