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Tag Archives: Evento scientifico

High gradient ultra-high brightness RF photoinjector optimization

Most of the accelerator applications demand an high beam quality: ultra low energy spread and ultra high beam brightness i.e. bunches with high peak current and ultra low emittance. These quality parameters are also necessary to perform a good matching between beams from a conventional accelerator and a plasma one in the so called external injection scheme. Beam brightness is a fundamental parameter for applications as the Free Electron Laser (FEL), where the gain length is inversely proportional to the electron beam brightness in the Self Amplified Spontaneous Emission (SASE) X-ray regime. These requests in the quality electron beam means that a perfect control of bunches along the beam line is necessary, starting from the bunch generation up to the accelerator end, especially in the photoinjector region where the beam is not yet relativistic and is in the so called space charge regime. From these requests an optimal transport has to be found i.e. an optimization of some parameters and distances has to be fixed: laser on cathode parameters a proper position for the first accelerating section, an integrated magnetic field of the gun solenoid and an optimal bunch compression scheme. To match these stringent beam quality parameter requests, I optimized the beam dynamics for a new ultra high gradient 1.6 cells C-band (5.712 GHz) gun able to reach 240 MV/m as a peak field. By means of the ultra high gradient a better control of the space charge forces inside the bunch is possible. After optimizations on this electron …

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KLOE-2 data-taking closing ceremony

All people involved in KLOE-2 activities, the DAFNE team,  former KLOE members, and LNF personnel are cordially invited to join the KLOE-2 data-taking closing ceremony   that will take place on March 30th at 11:00 in the Bruno Touschek Auditorium   PLEASE ACKNOWLEDGE YOUR PARTICIPATION BY REGISTERING TO THE EVENT!

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RF design of high gradient accelerating structures for high brightness electron linacs

In the framework of the upgrade of the SPARC_LAB facility at INFN-LNF, named EuPRAXIA@SPARC_LAB, a high gradient linac is foreseen. One of the most suitable options is to realize it in X-band. The EuPRAXIA@SPARC_LAB linac layout is based on an S-band Gun, three S-band TW structures and an X-band booster with a bunch compressor. In this presentation it is illustrated the preliminary RF design of the X-band booster. It is based on 0.5 m long traveling wave accelerating structures operating in the 2π/3 mode and fed by klystrons and pulse compressor systems.The design has been driven by the need of a high accelerating gradient required to achieve a high facility compactness, which is one of the main goals of the EuPRAXIA project. The single cell parameters have been calculated by electromagnetic simulations and, on the basis of these results, the accelerating structure length and geometry have been optimized by numerical studies. Finally, the basic RF power distribution layout has been designed.

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About Dark Matter scenarios in Composite Higgs Models and how to probe them

Non-minimal Composite Higgs Models feature additional scalars which can play the role of a dark matter candidate. These models are very predictive, since the requirement of the correct relic density bounds the new resonance mass from above. I will show that nearly the whole parameter space for such scenarios can be probed at future colliders and dark matter detection experiments.

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The time challenge: PICOSEC

The timing response of gaseous detectors is discussed with examples from past experiments. The concepts of the technique used for the PICOSEC project are discussed.

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The usefulness of useless science

If the scientific results financed by taxpayer money are “public goods”, is it useful or even ethical to spend billions Euros/$ to search for an elementary particle? Or to visit a Jupiter satellite and look for water on Mars? Or to observe a galaxy ad the edge of the Universe? In other words, is it useful to fund basic research? And if so, with what resources and to do what kind of science? Competition has become one of the major driving forces for research. But are we sure that the competition-driven science model is truly the best one to make useful science? More, is the very concept of knowledge changing today? The scientific method introduced by Galileo more that 400 years ago resisted at least three industrial revolutions. Are we sure is it still valid and applicable today, in the midst of the fourth industrial revolution? The answers to all these questions are not obvious, on the contrary, they can contain many surprises not all pleasant or reassuring, answers among which we will try to orient ourselves using an unconventional point of view.

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Gas detectors: general principles

Calorimetry in high-energy physics is rapidly evolving, with new specifications (e.g. higher energies, enormous particle densities) and a wide variety of technologies, both for signal creation and detection. Advances in large-area highly-segmented detectors based on, for example, silicon and scintillators, are providing possibilities for high-granularity calorimetry, providing unprecedented levels of information from particle showers. This talk focuses on one example of high-granularity calorimetry: The CMS HGCAL, being designed to replace the existing endcap calorimeters for the HL-LHC era. It is a sampling calorimeter, featuring unprecedented transverse and longitudinal readout segmentation for both electromagnetic (CE-E) and hadronic (CE-H) compartments. This will facilitate particle-flow calorimetry, where the fine structure of showers can be measured and used to enhance pileup rejection and particle identification, whilst still achieving good energy resolution. The CE-E and a large fraction of CE-H will use silicon as active detector material. The sensors will be of hexagonal shape, maximizing the available 8-inch circular wafer area. The lower-radiation environment will be instrumented with scintillator tiles with on-tile SiPM readout. This concept borrows heavily from designs produced by the CALICE collaboration – calorimetry for ILC etc. – but the challenges of such a detector at a hadron collider are considerably larger than at the ILC. In addition to the hardware aspects, the reconstruction of signals – both online for triggering and offline – is a quantum leap from existing detectors. We present the ideas behind the HGCAL, its current status including design and expected performance, and the challenges ahead.

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Gas detectors: general principles

Gas-based detectors measure the trajectories of charged particles through the ionisation electrons that are deposited in the gas. An electric field, and sometimes a magnetic field, guide(s) these electrons to amplification structures where an avalanche occurs. Avalanches produce electrons and ions and it is their motion that generates electric signals on the read-out electrodes. In this presentation we review these mechanisms.

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A Grand-Unified Nelson-Barr Model

I will discuss the structure of the Nelson-Barr approach to the strong CP Problem, and argue that these solutions can be naturally embedded into E6 Grand-Unified Theories, since the E6 fundamental contains all necessary fermions.The main benefit of the unified structure is the predictivity in the SM fermion sector, and a perfect fit to all SM observables can be obtained despite being over-constrained. Definite predictions are made for the neutrino sector, with a Dirac CP phase that is correlated to the CKM phase, allowing to test this model in the near future.

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High resolution TPC based on optically readout GEM

Large granularity and hight sensitivity commercial CMOS readout systems, open the possibility of developing particle detectors with very interesting performance for different applications, from the search of rare and exotics events, such as dark matter directional candidates, to high quality neutron/ion/hadron beam monitor, mainly for medical applications. This idea driven the CYGNUS group to exploit the gas scintillation mechanisms for starting an R&D on large TPC-based detector, equipped with a Triple GEM amplification stage optically readout. This approach, not only provides tracking capability with space resolutions of the order of tens of microns and energy measurements with a precision of about 25%, but also gives precious information allowing very good particle discrimination. Spectacular examples of captured images due to X-rays and high energy photons, cosmic muons, electrons from beam and neutrons interactions will be shown in this seminar together with quantitative analysis about the system performance.

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