Marco Bregant.

Estudo e desenvolvimento de detectores gasosos baseados em microestrutura (MPGD), eletrônica de leitura associada e aplicações.

Estudo e desenvolvimento de detectores gasosos baseados em microestrutura (MPGD), e da eletrônica de leitura associada.

Projeto de um ASIC de aquisição e processamento digital de sinais para o Time Projection Chamber do experimento Alice

Descrição: a colaboração ALICE é o único exerimento do acelerador LHC (Large Hadron Collider) inteiramente dedicado ao estudo da colisão entre íons pesados a energias relativísiticas. Esse experimento deve abrir novas fronteiras no estudo do Plasma de Quarks e Gluons com energias de colisão nunca atingidas antes..

ALICE (A Large Ion Collider Experiment) is one of the four main experiment at the CERN LHC. ALICE detector has been design to study the strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. The Subatech group is involved in the construction of the EMCal calorimeter. The research lines are jet physics and hight pt photon physics (aiming for gamma-jet studies). I contributed to the studies on background rejection in EMCAL via cuts applied to the time information. I contributed also, partially supervising a young post doc to the studies of EMCal cluster unfolding (reconstruction of Pi0 photon pair also in the case of partial overlapping photon clusters)

FINUDA experiment is located at the DAΦNE collider at Laboratori Nazionali di Frascati, Italy. DAΦNE is a Φ-factory which produces Φ(1020) at rest; the decay of Φ produces thus a low energy collinear couple K+K−. That allows to stop, with high ef- ficiency, K in thin targets, and thus to achieve a good momentum resolution. The aim of the FINUDA experiment was the study of the hypernucleus which forms when a K− stops inside a nucleus, generating an hyperon ( Λ or Σ). In FINUDA the vertex detector was based on microstrip detectors, thus I contributed in the detector operation and I took part at the data taking periods. I also contributed on the offline monitor of the trigger efficiency in rejecting background.

ALICE (A Large Ion Collider Experiment) is one of the four main experiment at the CERN LHC. ALICE detector has been design to study the strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions....

The core of ALICE detector is the inner tracking detectors and TPC. The Inner Tracking System (ITS) consist of six layers of silicon detectors. The two outermost layers are the Silicon Strip Detector. It is formed by 1698 double sidedsilicon microstrip modules, mounted on 72 ladders. When I joined the collaboration the design of the modules was not finalised yet, so I participated to the discussions, contributing to the final layout, also taking care of the assembling of some prototypes. The Trieste group was in charge to provide about 40% of the total amount of modules and I assumed the technical responsibility of this production done in a local company. The connection between the SSD sensor and its electronics is made by aluminium on kapton microcables bonded directly to the sensor and electronics (instead of the more common wire-bonding technique). I developed a protocol to verify via automatic optical inspection the quality and dimensions of microcable before their use, that allows to improve speed and reliability of the bonding processes. After the completion of the module production I contributed to the test of ladders before their assembling in the barrel shape. I was one of the deviser of the test protocol used to fully test the SSD detector. Since the detector was installed in its final position inside ALICE, I moved to CERN taking care of commissioning and integration of SSD with the ALICE systems (DAQ/Triggers/DCS). I was SSD Deputy Project Leader from 2008 till 2009.

PVLAS experiment goal is the measurement of the ellipticity gained by a linear polarised laser beam traversing, in vacuum, a transverse magnetic field region. The ellipticity is due to vacuum magnetic birefringence induced by the external field as predicted by QED, but can also be originated by light particles (mass ma < 10&#8722;3 eV) interacting with two photons. The experiment is based on an infrared laser (1064 nm), a very sensitive ellipsometer and a 6 T superconducting magnet which rotates around its axis so as to modulate the effect. The detection is performed using heterodyne technique, and a very high finesse 6-metres long Fabry-Perot cavity is used to amplify the effect. I contributed to the building of the experimental apparatus. I took care of setting up and tuning the ellipsometer, improving the the signal to noise ratio. That required to maximise the finesse of the cavity (and thus the amplification of the searched effect) and to fight aganist spurious effects coming mainly from a residual static birefringence due to imperfection in the optical elements. An optical cavity finesse around 100 000 was reached (it corresponds to about 65 000 passes through the magnetic field zone), while a sensitivity of the ellipsometer better than &#936;s &#8764; 4×10&#8722;7/&#8730;Hz was achieved. I contributed then at the developing and test of the locking circuit for a green laser which allows a second set of measurements at different wavelength (the searched effects amplitude depends on the light wavelength). The ellipsometer was first validated and calibrated by means of measurements of magnetic birefringence of gasses (Cotton-Mouton effect). A big effort was then made to identify and eliminate spurious sources of signals and systematic error in general. The sensitivity required for the QED effect was not reached, but new limits for the existence of lights particles which couple with two photons and on the photon-photon scattering were set.

The aim of the project MUH was the measurement of the hyperfine levels energy for muonic hydrogen (the bound system &#956;&#8722;p). The measurement of the 3D ? 3P energy difference provides a powerful test of QED vacuum polarisation. Muons were stopped in a low density hydrogen target, forming the bound system in an excited state. A tuneable free electron laser was supposed to &quot;pump? the hyperfine state, modifying the relative amplitudes of the K X-ray spectrum. The soft X-ray were detected by a CCD. I worked on the MonteCarlo simulation of a multipass optical cavity needed to uniform and enhanced the light intensity seen by the target. I also participated to preliminary measurements on K X-ray yields at low pressure