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Recently a new type of device, the MAPS-on-diamond, obtained bonding a thinned to 25 μm CMOS Monolithic Active Pixel Sensor to a standard 500 μm pCVD diamond substrate, has been proposed and fabricated, allowing a highly segmented readout (10×10 μm pixel size) of the signal produced in the diamond substrate. The bonding between the two materials has been obtained using a new laser technique to deliver the needed energy at the interface. A biasing scheme has been adopted to polarize the diamond substrate to allow the charge transport inside the diamond without disrupting the functionalities of the CMOS Monolithic Active Pixel Sensor. The main concept of this class of devices is the capability of the charges generated in the diamond by ionizing radiation to cross the silicon–diamond interface and to be collected by the MAPS photodiodes. In this work we demonstrate that such passage occurs and measure its overall efficiency. This study has been carried out first calibrating the CMOS MAPS with monochromatic X-rays, and then testing the device with charged particles (electrons) either with and without biasing the diamond substrate, to compare the amount of signal collected.

A new method of preparation of silicon-on-diamond materials is discussed in detail. Pre-characterization of the samples surfaces has been carried out, in order to calculate the optimal pressure for surface contact before the bonding process. The method is based on pulsed laser irradiation, in the 20 ps–7 ns range, at a wavelength of 355 nm, for which diamond is transparent and silicon highly absorbing. Under these conditions the material melts locally, within 100 nm at the interface, giving rise to amorphous silicon and silicon carbide. The mechanical strength of the bonding has been assessed by adhesion tests. Preliminary result on resistance to thermal annealing at 400 C in air is also reported. Uniformity of the silicon–diamond interface has been verified by scanning electron microscopy. Raman and infrared spectroscopy allowed to detect and estimate quantitatively the amorphous Si and SiC phases at the interface. A finite element simulation has been carried out, taking into account the processes occurring during the laser pulse and the subsequent cooling of the materials. As a result, energy densities per pulse required to melt locally diamond and silicon have been obtained as functions of the pulse width, giving a rationale to the formation of the SiC bond in terms of diamond–silicon inter diffusion. The experimental results of bondings performed at various energy density and pulse widths are in agreement with the model. The experimental results and the theoretical predictions are compared and discussed.

The characteristics of two hybrid step-down charge-pump voltage regulators (2.5, 1.25 V) are presented. The regulators feature a current multiplication factor 4 and two capacitor banks structure which allows to work easily in the megahertz region and with currents up to 1.5 A. Attention has been dedicated to the study of the power efficiency as a function of the frequency, in particular to the charge transfer factor leading to the voltage efficiency which has been fully described in an analytic way. This has allowed to evaluate possible improvements of the present prototypes.

Micro-fabrication in diamond is involved in a wide set of emerging technologies, exploiting the exceptional characteristics of diamond for application in bio-physics, photonics, radiation detection. Micro ion-beam irradiation and pulsed laser irradiation are complementary techniques, which permit the implementation of complex geometries, by modification and functionalization of surface and/or bulk material, modifying the optical, electrical and mechanical characteristics of the material. In this article we summarize the work done in Florence (Italy) concerning ion beam and pulsed laser beam micro-fabrication in diamond., 14 pages, 5 figures

A wavelength dispersive system based on a flat crystal coupled to a CCD position-sensitive detector is described. The system, to be used in conjunction with an external beam facility for PIXE measurements, is particularly compact, easy to use, and has a useful energy range extending from about 4 to 13 keV. The performance of the system with respect to efficiency and energy resolution is studied as a function of different experimental conditions. Possible simple applications are briefly discussed.

A recent laser bonding technique has been developed to prepare silicon-on-diamond material.This method allows the independent choice of the quality of the silicon and diamond plates to beprocessed. This opens a wide field of applications for silicon-on-diamond devices. We presentand discuss the laser technique and the experimental results achieved. Two new projects involvingrelevant issues both in high energy physics and in biological applications are also presented.

In this work we report on the characterization with ionizing radiation sources of a CMOS active pixel radiation sensor (RAPS03) thinned down to 40um and bonded to a slice of diamond to form a rugged Silicon-On-Diamond structure. The bonding process is based on an innovative laser technique which scans the silicon-diamond interface with a 20 ps pulsed 355 nm laser beam. The goal of the work is to demonstrate that the bonding procedure does not damage the CMOS devices, paving the way for a possible alternative to bump bonding procedures between diamond substrates and readout chips. To this purpose, the Silicon-On-Diamond device and a standard (e.g. un-thinned) RAPS03 sensor have been tested in parallel with and without ionizing radiation sources (photons, electrons) to compare their characteristics and to study their differences. The Silicon-On-Diamond device has shown to be fully functional and no differences have been found between the responses of the two sensors, within the statistical variations due to the CMOS fabrication process.

A position sensitive detector for minimum ionizing particles is described. It is based on charge coupled devices (CCDs) area image sensors with single pixel sizes of 22 × 22 μm2. The operating frequency is 6.75 MHz and the total readout time for 2.3 × 105 pixels is about 40 ms. The devices are operated close to room temperature.

Precise tracking information in the online selection of interesting physics events is extremely beneficial at hadron colliders. The CDF experiment at the Tevatron, has shown for the first time the impact of the tracking in triggers, allowing to achieve unprecedented precision in B-physics measurements. The CMS experiment at LHC will largely make use of tracking information at high level trigger, after the Level-1 acceptance. The increased luminosity of the Super-LHC collider will impose to CMS a drastic revision of the Level-1 trigger strategy, incorporating the tracker information at the first stage of the selection. After a review of the CDF and CMS approaches we will discuss several possible Level-1 tracker based concepts for the upgraded CMS detector at Super-LHC. One approach is based on associative memories, which has already been demonstrated in CDF. It makes use of binary readout in the front end electronics, followed by transfer of the full granularity data off detector using optical links to dedicated processors which reconstruct tracks.