Carla Vacchi

High-gain diode-pumped amplifier for generation of microjoule-level picosecond pulses.

A diode-pumped single-pass amplifier system relying on two grazing-incidence Nd:YVO(4) slabs was developed to increase the energy of low-repetition-rate pulses from a decimated low-power cw mode-locked oscillator. Single-pass unsaturated gain up to 1.3x10(5) was achieved, and amplified pulses of 10-muJ energy and 8.0-ps duration were obtained. Efficient second harmonic generation (SHG) at 532 nm was achieved, as well as traveling-wave parametric conversion in the range 770-1020 nm (signal) and 1110-1720 nm (idler).

Amplification of a low-power picosecond Nd:YVO/sub 4/ laser by a diode-laser side-pumped grazing-incidence slab amplifier

An optimized diode-laser side-pumped grazing-incidence Nd:YVO4 amplifier was used to increase the power of a 50-mW 150-MHz continuous-wave (CW)-pumped mode-locked oscillator up to 6.1 W in single pass, with 22% optical-to-optical efficiency, or up to 8.4 W in double pass, with 30% efficiency. Both beam quality (M2<1.4 from TEM00 seed pulses) and pulse duration (7.5 ps from 6.9 ps) were preserved. Single- or double-pass small-signal gain greater than 40 dB was achieved. These experimental results have been corroborated by a numerical model analysis of the amplifier

CHIPIX65: Developments on a new generation pixel readout ASIC in CMOS 65 nm for HEP experiments

Pixel detectors at HL-LHC experiments or other future experiments are facing new challenges, especially in terms of unprecedented levels of radiation and particle flux. This paper describes the progress made by the CHIPIX65 project of INFN for the development of a new generation readout ASIC using CMOS 65 nm technology.

Behavioural analysis of charge-pump PLL's

This paper presents a method for the numerical analysis of charge-pump Phase-Locked Loops in the time domain, using behavioural modelling of non-linear elements. The time domain is divided into intervals according to zero crossing of input and VCO signals. Inside each time interval, all signals in the network can be expressed with a set of functions made of complex polynomials and complex exponentials. A direct solution can be found, without requiring iterative procedures to converge. A computer program implementing the proposed analysis method has been written and applied to second- and third order PLLs.

Laser system generating 250-mJ bunches of 5-GHz repetition rate, 12-ps pulses.

We report on a high-energy solid-state laser based on a master-oscillator power-amplifier system seeded by a 5-GHz repetition-rate mode-locked oscillator, aimed at the excitation of the dynamic Casimir effect by optically modulating a microwave resonator. Solid-state amplifiers provide up to 250 mJ at 1064 nm in a 500-ns (macro-)pulse envelope containing 12-ps (micro-)pulses, with a macro/micropulse format and energy resembling that of near-infrared free-electron lasers. Efficient second-harmonic conversion allowed synchronous pumping of an optical parametric oscillator, obtaining up to 40 mJ in the range 750-850 nm.

The PixFEL project: development of advanced X-ray pixel detectors for application at future FEL facilities

The PixFEL project aims to develop an advanced X-ray camera for imaging suited for the demanding requirements of next generation free electron laser (FEL) facilities. New technologies can be deployed to boost the performance of imaging detectors as well as future pixel devices for tracking. In the first phase of the PixFEL project, approved by the INFN, the focus will be on the development of the microelectronic building blocks, carried out with a 65 nm CMOS technology, implementing a low noise analog front-end channel with high dynamic range and compression features, a low power ADC and high density memory. At the same time PixFEL will investigate and implement some of the enabling technologies to assembly a seamless large area X-ray camera composed by a matrix of multilayer four-side buttable tiles. A pixel matrix with active edge will be developed to minimize the dead area of the sensor layer. Vertical interconnection of two CMOS tiers will be explored to build a four-side buttable readout chip with small pixel pitch and all the on-board required functionalities. The ambitious target requirements of the new pixel device are: single photon resolution, 1 to 104 photons @ 1 keV to 10 keV input dynamic range, 10-bit analog to digital conversion up to 5 MHz, 1 kevent in-pixel memory and 100 μm pixel pitch. The long term goal of PixFEL will be the development of a versatile X-ray camera to be operated either in burst mode (European XFEL), or in continuous mode to cope with the high frame rates foreseen for the upgrade phase of the LCLS-II at SLAC.

210-

A single-pass two-stage Nd:YVO4 amplifier was used to increase the energy of a 7.7-ps seed pulse from < 1 nJ to 210 muJ (11-ps time duration), maintaining the input spatial quality of the pulse. The laser-diode side-pumped grazing-incidence Nd:YVO4 slab amplifier was optimized for minimum amplified spontaneous emission noise and for maximum energy extraction, with single-pass small-signal gain of 59 dB. Diffraction-limited operation up to 1 kHz is possible. Conversion efficiency of 75 % at 532 nm and 40% at 266 nm was observed.

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Natale Demaria∗† INFN Sezione di Torino, Torino, Italy E-mail: demaria@to.infn.it F.Ciciriello, F.Corsi, C.Marzocca Politecnico di Bari, Bari, Italy G.De Robertis, F.Loddo, C.Tamma INFN Sezione di Bari, Bari, Italy V.Liberali, S.Shojaii, A.Stabile INFN Sezione di Milano and Universita degli Studi di Milano, Milano, Italy M.Bagatin, D.Bisello, S.Gerardin, S.Mattiazzo, L.Ding, P.Giubilato, A.Paccagnella INFN Sezione di Padova and Universita di Padova, Padova, Italy F.De Canio, L.Gaioni, M.Manghisoni, V.Re, G.Traversi, E.Riceputi INFN Sezione di Pavia and Universita di Bergamo, Bergamo, Italy L.Ratti, C.Vacchi INFN Sezione di Pavia and Universita di Pavia, Pavia, Italy R.Beccherle, G.Magazzu, F.Morsani, F.Palla INFN Sezione di Pisa, Pisa, Italy G.M.Bilei, M.Menichelli INFN Sezione di Perugia, Perugia, Italy E.Conti, S.Marconi, D.Passeri, P.Placidi INFN Sezione di Perugia and Department of Engineering, Universita di Perugia, Italy G.Dellacasa, G.Mazza, A.Rivetti, M.D.Da Rocha Rolo INFN Sezione di Torino, Torino, Italy E.Monteil, L.Pacher INFN Sezione di Torino and University of Torino, Torino, Italy

J Picosecond Pulses From a Quasi-CW Nd:YVO

This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 μm. This work has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare (INFN), Italy.

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We report on the design and TCAD simulations of planar active-edge pixel sensors within the INFN PixFEL project. These devices are intended as one of the building blocks for the assembly of a multilayer, four-side buttable tile for X-ray imaging applications in future Free Electron Laser facilities. The requirements in terms of very wide dynamic range and tolerance to extremely high ionizing radiation doses call for high operation voltages. A comprehensive TCAD simulation study is presented, aimed at the best trade-offs between the minimization of the edge region size and the sensor breakdown voltage.