Search

We present the set-up and performances of the TOP-IMPLART accelerator as a proton source for radiation testing of space components. The TOP-IMPLART proton accelerator is a pulsed fully linear machine aimed at active intensity modulated proton therapy with a final energy of 150 MeV under development at ENEA Frascati Research Centre. Presently the machine offers a beam extraction point on the horizontal line at 35 MeV, with a current up to 50 µA in a 3 µs long pulse and maximum repetition frequency of 50 Hz. An in-air irradiation set-up 1.8 m downstream the accelerator exit window is available with an effective beam energy of about 30 MeV, ±5% transverse homogeneity on a 40 mm diameter beam spot, and intensity repeatability within ±5%. While the proton beams main characteristics (energy, intensity, average fluence) are the same of conventional cyclotron-based cancer treatment facilities, already used for space components qualification, its time structure is significantly different, with high instantaneous dose rate. This research aims at demonstrating the possibility to use an accelerator with these characteristics for radiation hardness assurance testing. A commercial 6-axis integrated MEMS inertial navigation system (accelerometer, gyroscope) was selected as device under test. These devices could be used for example as sensors for attitude determination in University Cubesat missions. Irradiation with proton beams allows simultaneous exploration of total dose, displacement damage and some single-event effect of such components. The results of experimental tests aimed to define an operational procedure are reported: the irradiation set-up is described in detail and the characterization of radiation effect on the component is reported highlighting the consequence of the device performance degradation in terms of the overall navigation system accuracy. These results are considered a first step towards the use of the TOP-IMPLART linear accelerator as a meaningful alternative to traditional cyclotron for proper space qualification of electronic components.

The aim of this work is to show a preliminary investigation of possible non-contact techniques for displacement measurement in a geological nuclear waste disposal. A nuclear waste repository can be considered as a harsh environment. This suggests the possibility to study alternative methods for measurement, for example methods not using cables or buses for detecting relevant data. A possible approach is substituting cables with wireless sensors. But if cables cannot be used and the use of wireless techniques is required, new sensors must assure reliable transmission without affecting the engineered barriers performance and the reliable use of energy supply for the measuring equipment over long periods. This work shows the results of a study on the possibility of using a Ground Penetrating Radar-like approach for the contactless displacement measurement of a container immersed and suspended in a material (bentonite) with a high degree of water retention

The purpose of the BIOxTREME project, launched by ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) and funded by ASI (Italian Space Agency), is to formulate new biological drugs having a stimulant activity on the immune system, finalizing the production for a "ready to use" resource in Bioregenerative Life Support Systems (BLSSs) for space missions intended for long-term duration, in deep space, and with multiple crews. One of the project tasks is to study the effects of physical insults on plants, trying to simulate cosmic environment on the production platforms exposing biological material to ionizing radiation, static magnetic fields and microgravity. In order to examine the biological effects, to test plant radio-resistance and to build dose-response curves we carried out proton irradiations of anthocyanin rich (red) "hairy roots" derived from the tomato cultivar Micro-Tom with different proton energies for several doses with the TOP-IMPLART accelerator at the ENEA Frascati Research center. The biological samples were placed in a holder specially made in a movable real-time monitoring chamber calibrated in dose. The fluence-homogeneity measurements over the sample and the calibration of the monitoring system were performed using GafChromic EBT3 films, placed in air in the same position as the biological samples to be irradiated. The present paper describes the experimental set-up and reports the preliminary results. Copyright © 2015 CC-BY-3.0 and by the respective authors.

In the ENEA-Frascati research center a linear accelerator for proton therapy is under development in the framework of TOP-IMPLART Project carried out by ENEA in collaboration with ISS and IRE-IFO. The machine is based on a 7 MeV injector operating at a frequency of 425 MHz followed by a sequence of 2997.92 MHz accelerating modules. Five 10 MW klystrons will be used to power all high frequency structures up to a beam energy of 150 MeV. The maximum repetition frequency is 100 Hz and the pulse duration is 4 μs. The RF amplitude and phase stability requirements of the accelerating field are within ±2% and ±2 degrees respectively. For therapeutic use the beam energy will be varied between 85 and 150 MeV by switching off the last modules and varying the electric field amplitude in the last module switched on. Fast control of the RF power supplied to the individual structures allows an energy variation on a pulse by pulse basis; furthermore the system must be able to control the RF phase between accelerating structures. This work describes the RF power distribution scheme and the RF phase and amplitude monitoring system implemented into an embedded control system. Copyright © 2015 CC-BY-3.0 and by the respective authors.

We have investigated the effects of deep hydrogen implantation into n- and p-type silicon wafers ((100) oriented, with resistivity in the 1-20 Ω·cm range). Deep implantation has been achieved using the Hitachi-AccSys PL-7 RF LINAC set for 3.0 MeV beam energy, degraded to 1.8 MeV. Hydrogen has been implanted 30 μm below the wafer surface with an implant dose (fluence) >5×1015 cm-2. Samples were partly covered by a metal mask during implant. Porous silicon has been formed on the exposed samples to study the effect of hydrogen irradiation. We have found that porous silicon formation is inhibited in the irradiated areas on p-type silicon and promoted on the n-type one. Copyright © 2015 CC-BY-3.0 and by the respective authors.

The TOP-IMPLART (Intensity Modulated Proton Linear Accelerator for Radio Therapy) proton linac, is a RF pulsed linac, designed for protontherapy consisting of a low frequency (425 MHz) 7 MeV injector followed by a sequence of accelerating modules operating at 3 GHz under construction, assembly and test at the ENEA Frascati Research Center. The accelerator features also a vertical low energy (3-7 MeV) line for irradiation of samples in horizontal position. The segment currently completed includes 8 SCDTL modules up to 71 MeV grouped in two sections each one powered by a 10 MW klystron driven by a SCANDINOVA K100 modulator with a variable pulse length (1-5 us) at a repetition frequency of 25 Hz. The output current can be varied up to 30 uA. The beam is mainly used for radiobiology experiments and dosimetry systems tests, but the flexibility in beam characteristics makes it suitable also for applications different from protontherapy, as the irradiation of electronics components to verify their behavior in the space environment. In this work, the current status of the accelerator and beam characteristics measurements are presented with an overview of the experiments carried on it., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

Solid-state radiation detectors based on the visible photoluminescence of radiation-induced F2 and F3+ color centers in lithium fluoride crystals have been used for advanced diagnostics of 18 and 27 MeV proton beams, produced by the TOP-IMPLART linear accelerator, which is under development for protontherapy applications at ENEA C.R. Frascati, Italy. Visible fluorescence microscopy was successfully used to read the latent proton beam images stored in the lithium fluoride crystals, thanks to high emission efficiency of the F2 and F3+ color centers obtained by simultaneous optical excitation in the blue spectral range. High intrinsic spatial resolution and wide dynamic range of these novel LiF detectors allow obtaining two-dimensional images of both the beam transverse intensity distribution and of the Bragg curve. By using a simple defect formation model that takes into account the energy released in the material and the saturation of defect concentration, not only the two-dimensional dose map was obtained from the beam transverse intensity distribution image, but also the full Bragg curve was reconstructed, allowing the thorough characterization of proton beams produced by the accelerator.

We present the first results of a novel collaboration activity between ENEA Frascati Particle Accelerator Laboratory and University La Sapienza Guidance and Navigation Laboratory in the field of Radiation Hardness Assurance (RHA) for space applications. The aim of this research is twofold: (a) demonstrating the possibility to use the TOP-IMPLART proton accelerator for radiation hardness assurance testing, developing ad hoc dosimetric and operational procedures for RHA irradiations; (b) investigating system level radiation testing strategies for Commercial Off The Shelf (COTS) components of interest for SmallSats space missions, with focus on devices and sensors of interest for guidance, navigation and control, through simultaneous exploration of Total Ionizing Dose (TID), Displacement Damage (DD) dose and Single-Event Effects (SEE) with proton beams. A commercial 6-axis integrated Micro Electro-Mechanical Systems (MEMS) inertial navigation system (accelerometer, gyroscope) was selected as first Device Under Test (DUT). The results of experimental tests aimed to define an operational procedure and the characterization of radiation effects on the component are reported, highlighting the consequence of the device performance degradation in terms of the overall navigation system accuracy. Doses up to 50 krad(Si) were probed and cross sections for Single-Event Functional Interrupt (SEFI) evaluated at a proton energy of 30 MeV.

The aim of this work is to show a preliminary investigation of possible noncontact techniques for displacement measurement of radioactive waste in a geological disposal. Since a nuclear waste repository can be considered as a harsh environment, the possibility to study alternative methods for measurement, for example, not using cables or buses for detecting relevant data, should be considered as a priority. A straightforward approach could be the substitution of cables with wireless sensors. But if cables cannot be used and the use of wireless techniques is required, new sensors must assure a reliable transmission without affecting the engineered barriers performance and the reliable use of energy supply for the measuring equipment over long periods. This work shows the results of a study of feasibility on using an electromagnetic (EM) approach for the contactless displacement measurement of a canister immersed and suspended in bentonite, a material with a high degree of water retention.

Spent nuclear fuel and high-level waste from fuel reprocessing are the most hazardous and long-lived radioactive wastes produced by the nuclear fuel cycle, and they must be contained and isolated for thousands of years at an acceptable safety level for human health and the environment. Recently, the authors have proposed a preliminary numerical investigation of possible non-contact techniques for displacement measurement in a geological nuclear waste disposal. In fact, cables used for the detection of measurement signals might be effectively substituted with wireless sensors, thus avoiding all the side effects produced in such a harsh environment (e.g. degradation due to temperature, humidity and radiation conditions). Previous works showed the feasibility of using an electromagnetic approach for the contactless displacement measurement of a canister immersed and suspended in bentonite, a material with a high degree of water retention. The results demonstrated that such an approach is possible provided that some strong requirements are imposed on the sensor design. Sure enough, new sensors must assure reliable transmission through the isolated areas of a repository without affecting the engineered barriers performance and reliable use of energy supply for the measuring equipment in the long term. This work proposes a possible experimental setup where the numerical models developed in previous works can be tested, so to arrive to a prototype sensor to be used in a demonstrator repository.

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.

Passive solid-state radiation detectors, based on the radiophotoluminescence of stable color centers in nominally pure lithium fluoride (LiF) crystals, have been used for advanced diagnostics of the segment up to 35 MeV of the TOP-IMPLART proton linear accelerator for protontherapy applications, under development at ENEA Frascati. In LiF, proton beams generate a spatial distribution of F2 and F3+ aggregate color centers, which efficiently emit radiophotoluminescence in the red-green spectral range under optical pumping around 450 nm. LiF crystals were irradiated with 35 MeV nominal energy protons at several doses of interest for protontherapy (from 0.5 to 50 Gy). For the first time is shown here the possibility of measuring the radiophotoluminescence spectra of proton irradiated LiF even at such low doses and how the signal showed a linear behavior with dose with a good signal-to-noise ratio. A Bragg-curve image, stored as color-center distribution in a LiF crystal after a 50 Gy-dose irradiation in a particular geometry, was acquired in a conventional fluorescence microscope. After appropriate image processing, the signal intensity resulted to be proportional to the linear energy transfer along the whole Bragg curve. By best-fitting it with an ad-hoc analytical formula, the depth-dose distribution was reconstructed and the proton beam energy and energy spread were estimated.

A short period undulator (1.4 cm) has been designed for the SPARC-FEL test facility and has been realized in collaboration with KYMA Srl. It has been installed on the undulator line at SPARC. The undulator, operating in a delta like mode, has been used as radiator in a segmented configuration. The first stage being provided by the five undulators of the SPARC FEL source "old" chain, with period 2.8 cm. The KYMA undulator has a quatrefoil structure, a high magnetic field homogeneity and focuses both in vertical and radial directions. The two sections, namely the bunching and radiating parts, are arranged in such a way that the second is adjusted on a harmonic of the first. Laser action occurring in the second part, is due to the bunching acquired in the first. Simulations of the temporal and spectral profiles in different electron beam operating conditions are reported, as well as the evolution of the longitudinal phase space. The agreement with the experimental results is discussed The importance of this experiment is at least threefold: 1) It proves that the segmented undulator can successfully be operated 2) It proves that the laser emission in the last undulator is entirely due to the bunching mechanism, being no second harmonic signal present in the first segment 3) Encourages various improvements of the configuration itself, as e.g. the use of a further undulator with variable magnetic field configuration in order to obtain a laser field with adjustable polarization. © 2015 SPIE.

We report the first experiment aimed at the demonstration of low-energy protons acceleration by a high-efficiency S-band RF linear accelerator. The proton beam has been accelerated from 7 to 11.6 MeV by a 1 meter long SCDTL (Side Coupled Drift Tube Linac) module powered with 1.3 MW. The experiment has been done in the framework of the Italian TOP-IMPLART (Oncological Therapy with Protons-Intensity Modulated Proton Therapy Linear Accelerator for Radio-Therapy) project devoted to the realization of a proton therapy centre based on a proton linear accelerator for intensity modulated cancer treatments to be installed at IRE-IFO, the largest oncological hospital in Rome. It is the first proton therapy facility employing a full linear accelerator scheme based on high-frequency technology. © CopyrightEPLA, 2015.