INFN Frascati National Laboratories Research Articles

The EuAPS Betatron Radiation Source: Status Update and Photon Science Perspectives

The EuPRAXIA EU project is at the forefront of advancing particle accelerator research and the development of photon sources through innovative plasma acceleration approaches. Within this framework, the EuAPS project aims to exploit laser wakefield acceleration to build and operate a betatron radiation source at the INFN Frascati National Laboratory. The EuAPS source will provide femtosecond X-ray pulses in the spectral region between about 1 and 10 keV, unlocking a realm of experimental ultrafast methodologies encompassing diverse imaging and X-ray spectroscopy techniques. This paper presents a description of the EuAPS betatron source, including simulations of the photon beam parameters, outlines the preliminary design of the dedicated photon beamline, and provides an insightful overview of its photon science applications.

The future search for low-frequency axions and new physics with the FLASH resonant cavity experiment at Frascati National Laboratories

We present a proposal for a new experiment, the FINUDA magnet for Light Axion SearcH (FLASH), a large resonant-cavity haloscope in a high static magnetic field which is planned to probe new physics in the form of dark matter (DM) axions, scalar fields, chameleons, hidden photons, as well as high frequency gravitational waves (GWs). Concerning the QCD axion, FLASH will search for these particles as the DM in the mass range (0.49–1.49)μeV, thus filling the mass gap between the ranges covered by other planned searches. A dedicated Microstrip SQUID operating at ultra-cryogenic temperatures will amplify the signal. The frequency range accessible overlaps with the Very High Frequency (VHF) range of the radio wave spectrum and allows for a search in GWs in the frequency range (100–300)MHz. The experiment will make use of the cryogenic plant and magnet of the FINUDA experiment at INFN Frascati National Laboratories near Rome (Italy); the operations needed to restore the functionalities of the apparatus are currently underway. We present the setup of the experiment and the sensitivity forecasts for the detection of axions, scalar fields, chameleons, hidden photons, and GWs.

The INFN-LNF present and future accelerator-based light facilities.

The INFN-Frascati National Laboratory (LNF) is nowadays running a 0.51 GeV electron-positron collider, DA NE, that also represents the synchrotron radiation source of the beamlines of the DA NE-Light facility. Not being DA NE dedicated to synchrotron radiations activities, the DA NE-Light facility can use it mainly in parasitic mode. Particle accelerators and high energy physics (HEP) have been and are the main core of the LNF research activity, but like other HEP international laboratories also LNF is now moving in the direction of developing a dedicated free electron laser (FEL) user facility, EuPRAXIA@SPARC_Lab, based on plasma acceleration. This new facility in the framework of the EuPRAXIA (European Plasma Research Accelerator with eXcellence in Applications) EU project should produce FEL radiation beams for a wide range of applications using a smaller accelerator compared to actual radio frequency-based accelerator sources dimensions.

The Investigation on the Dark Sector at the PADME Experiment

In this paper, we present the design and expected performance of the various detectors of the PADME experiment. The experiment design has been optimized for the detection of the final state photons produced along with a “Dark Photon”, decaying to invisible particles, in the annihilation a of 550 MeV positron with an atomic electron of a thin target. The PADME experiment has been built in a new dedicated experimental hall at the Beam Test Facility (BTF) of the INFN Frascati National Laboratories and has been taking data since the third quarter of 2018.

Proposal for Using DAΦNE as Pulse Stretcher for the Linac Positron Beam

The PADME experiment [1] aims at searching for the dark photon (A’) in the e+e− → Aγ′ process in a positron-on-target experiment, exploiting the positron beam of the DAΦNE Linac at the INFN Frascati National Laboratory (Italy). The Linac can provide a number of positrons in excess of 1010 in a 200 ns long pulse but, in order to keep the pile-up probability in the calorimeter at an acceptable level, the number of positrons for PADME has to be below 105/pulse, in particular by using the attenuating target in the BTF beam-line. The experiment is then essentially limited by the low duty factor (10−5 = 200 ns/20 ms). In this paper, an alternative proposal to use the DAΦNE positron ring as a Linac pulse stretcher, by injecting each pulse into the ring and extracting it by a slow resonant extraction using the m/3 resonance, is presented. This would allow for distributing the positrons of a single Linac pulse over a much longer time interval (0.2-0.5 ms), increasing the duty factor up to ∼1%. The required modifications of the DAΦNE positron transfer line and ring are described. A dedicated lattice for the positron ring has been designed and tracking of the positrons injected in the ring has been performed in order to optimize the extraction parameters and to give a preliminary estimate of the extracted beam characteristics.

The PADME calorimeters for missing mass dark photon searches

In this paper we will present the design and expected performance for the Electromagnetic and Small Angle Calorimeters (ECAL, SAC) of the PADME experiment. The design of the calorimeters has been optimized for the detection of the final state γ from the annihilation production (and subsequent “invisible” decay) of a “Dark Photon” produced by a positron beam on a thin, low Z target. Beam tests have been made in 2016 and 2017 at the INFN Frascati National Laboratories Linac Beam Test Facility (BTF) with positron beams of energy 100–400 MeV and results are presented. The PADME experiment will be built at the INFN Frascati National Laboratories by the end of 2017 and will be taking data in 2018 (and possibly also 2019). At the moment the collaboration is composed by the following institutions: INFN Roma and “La Sapienza” University of Roma, INFN Frascati, INFN Lecce and University of Salento, MTA Atomki Debrecen, University of Sofia, Cornell University, U.S. William and Mary College.

Diamond detectors with laser induced surface graphite electrodes

We report on the response of metal-less CVD polycrystalline-diamond pixel sensors under β-particles irradiation. A 21×21 array of 0.18×0.18mm2 pixels was realized on one side of a 10.0×10.0×0.5mm3 polycrystalline diamond substrate by means of laser induced surface graphitization. With the same technique, a large graphite contact, used for detector biasing, was fabricated on the opposite side. A coincidence detecting method was used with two other reference polycrystalline diamond detectors for triggering, instead of commonly used scintillators, positioned in the front and on the back of the sensor-array with respect to the impinging particles trajectory. The collected charge distribution at each pixel was analyzed as a function of the applied bias. No change in the pulse height distribution was recorded by inverting the bias voltage polarity, denoting contacts ohmicity and symmetry. A fairly good pixel response uniformity was obtained: the collected charge most probable value saturates for all the pixels at an electric field strength of about ±0.6V/μm. Under saturation condition, the average collected charge was equal to <Qcoll>=1.64±0.02fC, implying a charge collection distance of about 285µm. A similar result, within 2%, was also obtained for 400MeV electrons at beam test facility at INFN Frascati National Laboratory. Experimental results highlighted that more than 84% of impinging particles involved only one pixel, with no significant observed cross-talk effects.

Study of the single cluster response of a helium-isobutane drift chamber prototype using 8 keV X-rays

The identification of single clusters in the electronic signals produced by ionizing particles within a drift chamber is expected to significantly improve the performances of this kind of detectors in terms of particle identification capabilities and space resolution. In order to develop refined cluster recognition algorithms, it is essential to measure the response of the chamber and its electronics to single ionization clusters. This can be done by irradiating the chamber with X-rays. We report here on the studies performed on a drift chamber prototype for the MEG-II experiment at the X-ray facility of the INFN Frascati's National Laboratories ``XLab Frascati''. The prototype is operated with a helium-isobutane mixture and instrumented with high bandwidth custom pre-amplifiers. The results of this study have been used to develop an innovative method for cluster recognition, based on the Wiener filter technique, which has been tested on data collected at the Frascati's Beam Test Facility. As a side measurement, we also performed a study of the gas gain in a configuration which is similar to that of the MEG-II experiment.

Status and perspectives for the INFN Frascati National Laboratory

In the recent years a great effort has been done by the accelerator division in terms of research and development of new techniques of acceleration, new proposals on possible future accelerator related activities (IRIDE) and studies to improve the luminosity of the existing collider (DAΦNE). In parallel, the KLOE experiment has upgraded the detector installing an inner tracker to improve its reconstruction power in the vicinity of the vertex and a calorimeter system to improve its ability to distinguish kaon decays. In this paper I'll briefly summarize some of the most relevant activities taking place at the INFN Frascati National Laboratory and their possible future perspectives.

Measurements of leakage neutron spectra from a high-energy accumulation ring using Extended Range Bonner Sphere Spectrometers

Abstract Within the INFN–UAB cooperation, an experimental neutron spectrometry exercise was organized in DAΦNE, the high-energy Φ-meson producing accelerator (Φ-factory) of the INFN–Frascati National Laboratories. Particularly, the workplace neutron fields produced by a 510 MeV positron beam accumulated in the DAΦNE ring were characterized. As suitable instruments, the INFN and UAB Extended Range Bonner Sphere Spectrometers (ERBSS) were employed. These systems rely on different central detectors and have different sets of extended-range spheres. The experimental data were unfolded with the FRUIT unfolding code, especially designed for workplace measurements in absence of detailed pre-information on the neutron field. This analysis allowed studying the high-energy (>10 MeV) component of the neutron fields and assessing the performance of the two different ERBSS in this energy domain. Besides the discussion on ERBSS, this paper presents experimental data that may be used in radiation protection of high-energy positron beams.

Neutron dosimetry at a high-energy electron–positron collider†

Electron–positron colliders with energy of hundreds of MeV per beam have been employed for studies in the domain of nuclear and sub-nuclear physics. The typical structure of such a collider includes an LINAC, able to produce both types of particles, an accumulator ring and a main ring, whose diameter ranges from several tens to hundred meters and allows circulating particle currents of several amperes per beam. As a consequence of the interaction of the primary particles with targets, shutters, structures and barriers, a complex radiation environment is produced. This paper addresses the neutron dosimetry issues associated with the operation of such accelerators, referring in particular to the DAΦ NE complex, operative since 1997 at INFN–Frascati National Laboratory (Italy). Special attention is given to the active and passive techniques used for the spectrometric and dosimetric characterization of the workplace neutron fields, for radiation protection dosimetry purposes. †Paper presented as a contribution to the 10th International Symposium on Solid State Dosimetry, Mexico City (24–28 September 2007).

PRESS-MAG-O: A new facility to probe materials and phenomena under extreme conditions

In the recent years, several experiments performed under high magnetic fields (HMFs), at high pressure (HP) and/or at low temperature (LT) have led to spectacular discoveries in condensed matter. In many new systems, although challenging, it is strategic to perform a magneto-optical analysis, to investigate the phonon behavior in the far infrared (IR) domain. By combining HMF and HP in a wide temperature ( T) range to perform concurrently IR magneto-optics and ac-magneto-dynamic experiments, it will be possible to achieve unique information on systems and/or new phenomena, almost impossible to obtain with standard spectroscopic methods. Here we present PRESS-MAG-O, a new facility under construction that will perform HP experiments under HMF in a wide T range. The system is expected to be operational by the end of 2008 and will be tested at SINBAD, the IR synchrotron radiation beamline operational since 2001 at DAΦNE (Double Annular Φ-factory for Nice Experiments), the storage ring of the INFN Frascati National Laboratory (LNF). While for IR experiments an interferometer will be used, for the magneto-dynamic experiments a SQUID magnetometer in the 10 Hz–2 KHz frequency range will be utilized. HP will be applied to samples by a Cu–Be diamond anvil cell (DAC), so that the device will be able to collect FTIR spectra and high harmonic ac susceptibility data in a dc magnetic field up to 8 T and to about 20 GPa in a wide temperature range (4.2–200 K).

Monitoring the ambient neutron radiation around a high energy electron/positron collider using PADC dosemeters

At the INFN Frascati National Laboratories (INFN-LNF), the DA Φ NE accelerator complex for fundamental and applied physics is operating since 1997. The routine radiation protection monitoring of the ambient neutron radiation around the accelerator is performed by means of a homemade dosimetry service, based on chemically etched PADC detectors. The LNF dosemeter is based on a four-element configuration, in which the main characteristic is a new procedure to reduce the fraction of “false positives”, i.e. background dosemeters inferred as doses due to spurious high track densities. The calibration of the dosemeters has been performed with a standard 241Am-Be neutron field. In addition, field-specific calibration factors have been derived, relying on the measured neutron spectra in selected workplaces around the accelerator. This work shows the results of the first two months monitoring period and discusses the suitability of the PADC for the neutron dosimetry around particle accelerators. The implications in the accuracy of the measurement, due to the realistic calibration and the new four elements configuration, are also addressed.

The new PADC based fast neutron dosimetry system of the INFN—LNF

At the Radiation Protection Laboratory of the INFN—Frascati National Laboratories, a new polyallyl diglycol carbonate (PADC) based fast neutron dosimetry system has been established for the routine monitoring of ambient neutron radiation around the 510 MeV e + / e - DA Φ NE collider as well as research activities in the field of neutron dosimetry. The detectors, supplied by Intercast (Parma, Italy), are processed by means of a two-stage chemical etching. The analysis is performed with a new automated reader, developed at the laboratory under the Labview (National Instruments) environment. Taking advantage of a set of automated motion, vision and regulation procedures, this system provides very reproducible, accurate and quick results suitable for both investigation and routine purposes. Moreover, the adoption of a four element configuration combined with a deep study of the background distribution, allows obtaining a minimum detectable ambient dose equivalent as low as 30 μ Sv . This work analyzes the dosimetric performance of the LNF ambient dosemeter as well as the characteristics of the LNF new reading system.

FRUIT: An operational tool for multisphere neutron spectrometry in workplaces

FRUIT (Frascati Unfolding Interactive Tool) is an unfolding code for Bonner sphere spectrometers (BSS) developed, under the Labview environment, at the INFN-Frascati National Laboratory. It models a generic neutron spectrum as the superposition of up to four components (thermal, epithermal, fast and high energy), fully defined by up to seven positive parameters. Different physical models are available to unfold the sphere counts, covering the majority of the neutron spectra encountered in workplaces. The iterative algorithm uses Monte Carlo methods to vary the parameters and derive the final spectrum as limit of a succession of spectra fulfilling the established convergence criteria. Uncertainties on the final results are evaluated taking into consideration the different sources of uncertainty affecting the input data. Relevant features of FRUIT are (1) a high level of interactivity, allowing the user to follow the convergence process, (2) the possibility to modify the convergence tolerances during the run, allowing a rapid achievement of meaningful solutions and (3) the reduced dependence of the results from the initial hypothesis. This provides a useful instrument for spectrometric measurements in workplaces, where detailed a priori information is usually unavailable. This paper describes the characteristics of the code and presents the results of performance tests over a significant variety of reference and workplace neutron spectra ranging from thermal up to hundreds MeV neutrons.

Performance of the UAB and the INFN-LNF Bonner sphere spectrometers in quasi monoenergetic neutron fields

In the framework of collaboration between the Universidad Autónoma de Barcelona and the INFN Frascati National Laboratories, an experimental Bonner Sphere neutron spectrometry exercise has been performed in the 2.5 MeV and 14.2 MeV quasi monoenergetic neutron beams of the ENEA Fast Neutron Generator. The neutron spectra at given distances from the accelerator target have been determined, taking advantage of the new unfolding FRUIT code, recently developed by the LNF group. The results show a good coherence between the two spectrometers, and between the measured and simulated data.

Determination of the response to photons and thermal neutrons of new LiF based TL materials for radiation protection purposes

LiF based thermoluminescent materials are the most used passive detectors in the field of radiation protection. For personal and area dosimetry in mixed neutron and photon fields, /sup 6/LiF and /sup 7/LiF TLD pairs are employed for the simultaneous determination of neutron and photon doses. Therefore, an accurate knowledge of their sensitivity to photons and thermal neutrons is essential. Aimed at providing reliable sensitivity data for new LiF based TL materials, an experimental study was performed in the framework of collaboration between INFN Frascati National Laboratories and ENEA, Italy. The /sup 6/LiF(Mg, Cu, P) material from TLD Poland, was specially manufactured in six versions with different sensitive thickness (t=40,60,80,100,150 and 230 mg/spl middot/cm/sup -2/), which implies different neutron and photon sensitivity. Together with the /sup 7/LiF(Mg, Cu, P) material, namely MCP-7, all seven type of TLDs were irradiated in reference beams of photons and thermal neutrons, at the calibration facilities of INFN and ENEA. The study provides a set of sensitivity data and discusses the performance of the investigated materials for the dosimetry of mixed neutron and photon fields. All uncertainties or error bars reported in the paper refer to 95% confidence level (2 sigma).

The FINUDA superconducting magnet at DAΦNE

FINUDA is an experiment aiming at high resolution hypernuclear spectroscopy. It employs different types of detectors enclosed inside a large superconducting solenoid. It will operate on the new, high luminosity ( e + − e −) collider DAΦNE of the INFN Frascati National Laboratory. The solenoid operates at 2765 A maximum current corresponding to a magnetic field of 1.1 T. The inner dimensions are: 2.4 m length, 2.7 m diameter. The coil within its cryostat is enclosed inside an iron return yoke composed by a central barrel and two end-caps which can be opened to access the inner detectors. The magnetic field in the inner volume has been fully mapped for both main and minor components. The alignment of such a magnet on a machine as DAΦNE is a very crucial item, needing particular care.

Gas bremsstrahlung evaluations for a phi-factory.

Gas bremsstrahlung from the phi-Factory presently under construction at the INFN Frascati National Laboratories (Italy) has been studied using the Monte Carlo FLUKA code. Photon spectrum and quantitative estimates of fluence rates and tissue absorbed dose rates are given. On the basis of the obtained results the precautions to be taken are discussed.