The INFN Laboratori Nazionali di Frascati was established in 1954 to host an electro-synchrotron, the first particle accelerator built in Italy, and since then played a crucial role in the field of nuclear and particle physics and for the development of acceleration and detection technologies. Within this historical tradition, a workshop was organized at LNF in the framework of the Nuclear Physics Mid Term Plan Italy, an initiative of the Nuclear Physics Division of the Istituto Nazionale di Fisica Nucleare, to discuss the detection techniques employed in nuclear physics and to identify the open issues to be addressed to realize the scientific programs of the experiments foreseen in a midterm perspective. The present report summarizes the outcome of the discussions.

We investigate the activation yield and optical properties of the negatively charged nitrogen-vacancy (NV (-)) and silicon-vacancy (SiV (-)) centers in single-crystal diamonds, focusing on the effect of proton (p) and carbon-ion (C) irradiation on their formation. The samples, either nitrogen-rich or silicon-implanted, are grown by chemical vapor deposition or high pressure-high temperature synthesis. They are irradiated over three orders of magnitude in fluence, up to similar to 10(14)C/cm(2) or similar to 10(16) p/cm(2), generating up to similar to 10(4) ppm of extra vacancies at the end-of-range. Following thermal annealing at 1150 degrees C for 1 h, we characterize the samples using time-resolved spectroscopy, optical spectroscopy, and optically detected magnetic resonance. The optical properties of the NV (-) and SiV- centers remain stable even at vacancy concentrations of similar to 10(3)-10(4) ppm. At the same time, the activation yield of substitutional nitrogen and (primarily) interstitial silicon increases significantly with vacancy density, from below 2 % to approximately 15-20 % for both centers. A statistical model of defect dynamics during annealing accounts for these results, showing that the activation yield follows a logarithmic dependence on local vacancy concentration-extending over three decades for NV (-) and two for SiV (-).

Color centers in diamond are promising systems for quantum technologies and nanophotonics as they are photostable emitters at room and elevated temperatures. The possibility of their electrical excitation has already been demonstrated within diodes. However, this requires the growth of complex diamond structures. In contrast to these conventional approaches, we demonstrate the emission from color centers under electrical pumping in a Schottky diode configuration based on -type diamond. Hydrogen passivation allows the modification of the Schottky barrier height and improves the injection of minority charge carriers needed for the electrical pumping, while electrons are provided by the -type layer.

Single-color centers in thin polycrystalline diamond membranes allow the platform to be used in integrated quantum photonics, hybrid quantum systems, and other complex functional materials. While single-crystal diamond membranes are still technologically challenging to fabricate as they cannot be grown on a non-diamond substrate, free-standing polycrystalline diamond membranes can be conveniently fabricated at large-scale from nanocrystalline diamond seeds on a substrate that can be selectively etched. However, their practical application for quantum photonics is so far limited by crystallographic defects, impurities, graphitic grain boundaries, small grain sizes, scattering loss, and strain. In this paper, we report on a single-photon source based on silicon-vacancy color centers in a polycrystalline diamond membrane. We discuss the spectroscopic approach and quantify the photon statistics, obtaining a g2(0) ≈ 0.04. Our findings hold promise for introducing polycrystalline diamond to quantum photonics and hybrid quantum systems.

A robust quantum light source operating upon electrical injection at ambient conditions is desirable for practical implementation of quantum technologies, such as quantum key distribution or metrology. Color centers in diamond are promising candidates as they are photostable emitters at room and elevated temperatures. The possibility of their electrical excitation has already been demonstrated within p-i-n diodes. However, this requires the growth of complex diamond structures. In contrast to these conventional approaches, we demonstrate the emission of color centers under electrical pumping in a novel Schottky diode configuration based on hydrogen passivated n-type diamond, which holds promise for integrated single-photon emitting devices based on color centers in diamond.

Track reconstruction at future hadronic colliders such as FCC-hh poses non negligible challenges due to the expected unprecedented levels of radiation affecting the tracking detectors. Detectors featuring excellent spatial and time resolution as well as very high radiation hardness are deemed to be essential for efficient tracking at future experiments. 3D Diamond pixel sensors are considered very promising candidates to fulfil these requirements as they pair the well known excellent timing characteristics and radiation hardness of diamond. We report on the timing characterisation of innovative 3D pixel diamond detectors with electrodes obtained by a laser graphitisation technique optimised for high time resolution. Results of a test beam provide for the first time a time resolution well below 100 ps with an efficiency larger than 99%. Hybridisation of the sensors with a dedicated timing ASIC is also presented for the first time.

We present a study on the radiation tolerance and timing properties of 3D diamond detectors fabricated by laser engineering on synthetic Chemical Vapor Deposited (CVD) plates. We evaluated the radiation hardness of the sensors using Charge Collection Efficiency (CCE) measurements after neutron fluences up to 1016 n/cm2 (1 MeV equivalent.) The radiation tolerance is significantly higher when moving from standard planar architecture to 3D architecture and increases with the increasing density of the columnar electrodes. Also, the maximum applicable bias voltage before electric breakdown increases significantly after high fluence irradiation, possibly due to the passivation of defects. The experimental analysis allowed us to predict the performance of the devices at higher fluence levels, well in the range of 1016 n/cm2. We summarize the recent results on the time resolution measurements of our test sensors after optimization of the laser fabrication process and outline future activity in developing pixel tracking systems for high luminosity particle physics experiments.

Tracking detectors for the future hadronic machines are expected to stand an extreme level of radiation and to provide at the same time high space and time resolutions. Diamond detectors satisfy both of the latter requirements and, in addition, a 3D geometry with thin columnar resistive electrodes orthogonal to the diamond surface enhances the natural radiation tolerance and response speed of this material. We report on the timing characterization of a 3D pixel diamond detector prototype fabricated, by laser graphitization with a 55 x 55 mu m(2) pixel geometry, in Firenze. Results of a tests beam provide a time resolution well below 100 ps with an efficiency larger than 99%.

Diamond is used as detector material in high energy physics experiments due to its inherent radiation tolerance. The RD42 collaboration has measured the radiation tolerance of chemical vapour deposition (CVD) diamond against proton, pion, and neutron irradiation. Results of this study are summarized in this article. The radiation tolerance of diamond detectors can be further enhanced by using a 3D electrode geometry. We present preliminary results of a poly-crystalline CVD (pCVD) diamond detector with a 3D electrode geometry after irradiation and compare to planar devices of roughly the same thickness.

High time resolution and extreme radiation hardness are key for detectors to be operated in future particle accelerators and in space or medical applications. With respect to these relevant properties, we report here on performances of pixel sensors prepared on mono- and poly-crystalline synthetic Chemical Vapor Deposited (CVD) diamonds, by fast laser modification via multiphoton absorption from a 50 fs, 800 nm, Ti:Sa source. The research has been carried out in the framework of the Timespot experiment of the Italian National Institute for Nuclear Physics (INFN) aimed to achieve both high spatial resolution (55 μm pitch) and very high time resolution (tens of picoseconds) with very radiation tolerant detectors. Timespot exploits the recent 3D electrode architecture to enhance both time resolution and radiation hardness with respect to standard planar silicon and diamond detectors. We present here a major step forward in material engineering and fabrication procedure, yielding a time resolution improvement of our devices from the initial 280 ps to the present 80 ps, bringing this figure of merit very close to that allowed by the more mature 3D silicon technology. Recent results will be presented, and strategies for further improvements will be discussed. Since diamond is known to be a very radiation-tolerant material, it is considered very promising for implementing devices planned for very fast response and radiation hardness. We present results on a thorough study of polycrystalline and monocrystalline diamond sensors irradiated up to a fluence level of 1016 neq (1 MeV)/cm2. The superior radiation hardness of the 3D architecture is demonstrated with respect to the planar detectors. We have also verified that the radiation hardness increases with increasing bulk electrode density. The results are discussed and compared with other radiation hardness studies carried out on 3D diamond sensors.

Light emission from color centers in diamond is being extensively investigated for developing, among other quantum devices, single-photon sources operating at room temperature. By doping diamond with phosphorus, one obtains an n-type semiconductor, which can be exploited for the electrical excitation of color centers. Here, we discuss the optical properties of color centers in phosphorus-doped diamond, especially the silicon-vacancy center, presenting the single-photon emission characteristics and the temperature dependence aiming for electroluminescent single-photon emitting devices.

Purpose: Small photon beams used in radiotherapy techniques have inherent characteristics of charge particle disequilibrium and high-dose gradient making accurate dosimetry for such fields very challenging. By means of a 3D manufacturing technique, it is possible to create arrays of pixels with a very small sensitive volume for radiotherapy dosimetry. We investigate the impact of 3D pixels size on absorbed dose sensitivity, linearity of response with dose rate, reproducibility and beam profile measurements.Methods: Diamond detectors with different pixel sizes have been produced in the 3DOSE experiment framework. To investigate the pixels size impact, they were tested using an Elekta Synergy LINAC. Dose rate dependence, absorbed dose sensitivity, reproducibility and beam profile measurement accuracy have been investigated and compared with PTW 60019 and IBA SFD reference dosimeters.Results: All of the 3D pixels had a linear and reproducible response to the dose rate. The sensitivity of a pixel decreases with its size, although even the smallest pixel has a high absorbed dose sensitivity (15 nC/Gy). The penumbra width measured with the smallest pixel size was consistent with the PTW microDiamond and differed by 0.2 mm from the IBA SFD diode.Conclusions: The study demonstrates that variation in pixel size do not affect the linearity of response with dose rate and the reproducibility of response. Due to the 3D geometry, the absorbed dose sensitivity of the detector remains high even for the smallest pixel, furthermore the pixel size was demonstrated to be of fundamental importance in the measurement of beam profiles.

The controlled creation of quantum emitters in diamond represents a major research effort in the fabrication of single-photon devices. Here, we present the scalable production of silicon-vacancy (SiV) color centers in single-crystal diamond by ion implantation. The lateral position of the SiV is spatially controlled by a 1-$\mu$m pinhole placed in front of the sample, which can be moved nanometer precise using a piezo stage. The initial implantation position is controlled by monitoring the ion beam position with a camera. Hereby, silicon ions are implanted at the desired spots in an area comparable to the diffraction limit. We discuss the role of ions scattered by the pinhole and the activation yield of the SiV color centers for the creation of single quantum emitters.

Phosphorus-doped diamond is relevant for applications in sensing, optoelectronics and quantum photonics, since the unique optical properties of color centers in diamond can be combined with the n-type conductivity attained by the inclusion of phosphorus. Here, we investigate the photoluminescence signal of the nitrogen-vacancy and silicon-vacancy color centers in phosphorus-doped diamond as a function of temperature starting from ambient conditions up to about 100$^\circ$ Celsius, focusing on the zero-phonon line (ZPL). We find that the wavelength and width of the ZPL of the two color centers exhibit a comparable dependence on temperature, despite the strong difference in the photoluminescence spectra. Moreover, the temperature sensitivity of the ZPL of the silicon-vacancy center is not significantly affected by phosphorus-doping, as we infer by comparison with silicon-vacancy centers in electronic-grade single-crystal diamond.

Silicon-vacancy (SiV) centers in diamond are gaining an increased interest for application, such as in quantum technologies and sensing. Due to the strong luminescence concentrated in its sharp zero-phonon line at room temperature, SiV centers are being investigated as single-photon sources for quantum communication, and also as temperature probes for sensing. Here, we discussed strategies for the fabrication of SiV centers in diamond based on Si-ion implantation followed by thermal activation. SiV color centers in high-quality single crystals have the best optical properties, but polycrystalline micro and nanostructures are interesting for applications in nano-optics. Moreover, we discuss the photoluminescence properties of SiV centers in phosphorous-doped diamond, which are relevant for the creation of electroluminescent devices, and nanophotonics strategies to improve the emission characteristics of the SiV centers. Finally, the optical properties of such centers at room and high temperatures show the robustness of the center and give perspectives for temperature-sensing applications.

The LABEC laboratory, the INFN ion beam laboratory of nuclear techniques for environment and cultural heritage, located in the Scientific and Technological Campus of the University of Florence in Sesto Fiorentino, started its operational activities in 2004, after INFN decided in 2001 to provide our applied nuclear physics group with a large laboratory dedicated to applications of accelerator-related analytical techniques, based on a new 3 MV Tandetron accelerator. The new accelerator greatly improved the performance of existing Ion Beam Analysis (IBA) applications (for which we were using since the 1980s an old single-ended Van de Graaff accelerator) and in addition allowed to start a novel activity of Accelerator Mass Spectrometry (AMS), in particular for 14 C dating. Switching between IBA and AMS operation became very easy and fast, which allowed us high flexibility in programming the activities, mainly focused on studies of cultural heritage and atmospheric aerosol composition, but including also applications to biology, geology, material science and forensics, ion implantation, tests of radiation damage to components, detector performance tests and low-energy nuclear physics. This paper describes the facilities presently available in the LABEC laboratory, their technical features and some success stories of recent applications.

Synthesis of diamond by Chemical Vapour Deposition (CVD) was achieved already in the 60s, but applications became viable only in the 80–90s due to a significant improvement of the technique in which the substrate temperature was decoupled from the gas phase temperature leading to an increase of orders of magnitude in growth rates [1]. The CVD technique offered a superior control of the purity of the material with respect to natural and High-Pressure High-Temperature synthetic diamond, in particular limiting to atomic ppb the unwanted inclusion of substitutional N and N aggregates which severely deteriorate the electronic properties of the material. A huge industrial scale-up toward high technology applications was forecasted to happen in the 2000s [2], thanks to the extreme physical properties of the material, suitable for countless applications. Yet, that revolution did not happen and the field is still strongly limited by the polycrystalline nature of the material growth on non-diamond substrates, which severely impairs the electronics applications. Applications of homoepitaxially grown monocrystalline material is also strongly limited because the material itself can be fabricated with a maximum size of about 1 cm, due the availability of diamond substrates and by the cost of the production. In addition, monocrystalline samples are also affected by structural defects, such as dislocations, that degrade their optical and electronic response. Heteroepitaxial growth of large area monocrystalline samples has been recently reported [3]. Although the electronic properties of this material are still lower quality than those of the homoepitaxial one [4], optimization is underway. Heteroepitaxial material seems the only viable solution for a future widespread development of diamond applications. Nevertheless, many interesting applications of CVD diamond are already possible at present and others that offer the promise of a major breakthrough, are intensively investigated. Among the latter, the concept of diamond power electronics, although still limited by the considerable depth of the dopant (P,B) levels [5], is extremely promising. Particularly appealing is the development of fast electronics operated without need of cooling and offering the possibility of integrating diamond sensors with diamond readout electronics in compact and extremely radiation tolerant devices. In this Topic we address some of the CVD diamond applications which seem more mature. Diamond sensors for high resolution timing application have been used (Minafra et al.) in high energy experiments to reconstruct particle trajectories and measure their arrival time, profiting of the radiation hardness and the high saturation velocities of the material. A three-dimensional electrode architecture has been proposed within the TimeSpot experiment both for diamond and silicon particle detectors where the drift path of the ionization carriers towards the electrodes is strongly shortened. In this way the influence of the crystal defects as well as the charge collection times are substantially reduced resulting in some of the fastest [5] and radiation hardest [6] radiation sensors ever fabricated. Anderlini et al. summarize the results obtained so far on 3D diamond detectors Edited and reviewed by: Cinzia Da Via, The University of Manchester, United Kingdom

Diamond color centers represent a promising resource for quantum photonics applications. Various approaches based on ion implantation have been developed for their controlled creation, but only at shallow depths. In article number 2100079, Lukas Hunold, Mario Agio, and co-workers show the ability to produce diamond color centers with a lateral precision of 1 µm at depths down to 1 µm and they discuss methods to improve the resolution further. These findings facilitate the post-fabrication of photonic structures and post-processing of diamond-based devices.

Tracking detectors at future high luminosity hadron colliders are expected to be able to stand unprecedented levels of radiation as well as to efficiently reconstruct a huge number of tracks and primary vertices. To face the challenges posed by the radiation damage, new extremely radiation hard materials and sensor designs will be needed, while the track and vertex reconstruction problem can be significantly mitigated by the introduction of detectors with excellent timing capabilities. Indeed, the time coordinate provides extremely powerful information to disentangle overlapping tracks and hits in the harsh hadronic collision environment. Diamond 3D pixel sensors optimised for timing applications provide an appealing solution to the above problems as the 3D geometry enhances the already outstanding radiation hardness and allows to exploit the excellent timing properties of diamond. We report here the first full timing characterisation of 3D diamond sensors fabricated by electrode laser graphitisation in Florence. Results from a 270MeV pion beam test of a first prototype and from tests with a β source on a recently fabricated 55×55μm2 pitch sensor are discussed. First results on sensor simulation are also presented.