Resonance frequency shift in a cavity with a thin conducting film near a conducting wall

We show that a very thin conducting film (whose thickness can be much smaller than the skin depth), placed nearby a wall of an electromagnetic cavity, can produce the same shift of the resonance frequency as a bulk conducting slab, provided the displacement of the film from the wall is much bigger than the skin depth. We derive a simple analytical formula for the frequency shift and compare it with exact numerical calculations and experimental data

Early clinical experience with volumetric modulated arc therapy in head and neck cancer patients

<p>Abstract</p> <p>Background</p> <p>To report about early clinical experience in radiation treatment of head and neck cancer of different sites and histology by volumetric modulated arcs with the RapidArc technology.</p> <p>Methods</p> <p>During 2009, 45 patients were treated at Istituto Clinico Humanitas with RapidArc (28 males and 17 females, median age 65 years). Of these, 78% received concomitant chemotherapy. Thirty-six patients were treated as exclusive curative intent (group A), three as postoperative curative intent (group B) and six with sinonasal tumours (group C). Dose prescription was at Planning Target Volumes (PTV) with simultaneous integrated boost: 54.45Gy and 69.96Gy in 33 fractions (group A); 54.45Gy and 66Gy in 33 fractions (group B) and 55Gy in 25 fractions (group C).</p> <p>Results</p> <p>Concerning planning optimization strategies and constraints, as per PTV coverage, for all groups, D_98%> 95% and V_95%> 99%. As regards organs at risk, all planning objectives were respected, and this was correlated with observed acute toxicity rates. Only 28% of patients experienced G3 mucositis, 14% G3 dermitis 44% had G2 dysphagia. Nobody required feeding tubes to be placed during treatment. Acute toxicity is also related to chemotherapy. Two patients interrupted the course of radiotherapy because of a quick worsening of general clinical condition.</p> <p>Conclusions</p> <p>These preliminary results stated that volumetric modulated arc therapy in locally advanced head and neck cancers is feasible and effective, with acceptable toxicities.</p

One-cm-thick Si detector at LHe temperature

A silicon p-i-n diode of thickness 1 cm has been studied experimentally at liquid helium temperature. This preliminary study is aimed at the construction of a much bigger detector to detect low energy neutrino events

Massive silicon or germanium detectors at cryogenic temperature

Several massive silicon and germanium home-made detectors, working at cryogenic temperature, have been studied. They are the benchmarking schemes to check the possibility of realizing a semiconductor time projection chamber that could have various interesting applications in weak interaction problems. Reported here are the first results on investigations of charge collection efficiency and metal\u2013semiconductor contact hardness. The leakage current, total depletion voltage and alpha or gamma spectroscopy are presented

Characterization of a low noise microwave receiver for the detection of vacuum photons

In this work we present measurements of the sensitivity of a low noise microwave receiver developed with the aim to detect a feeble quantum electrodynamics effect known as dynamical Casimir effect. We study the performance of the receiver when it is connected to a transmission line ending with an antenna coupled to a resonant microwave cavity. The noise temperature of the receiver is measured with the method of the variable temperature load resistor. The noise generated by the cavity is measured in a similar way. An equivalent input noise of 2 10^-22 W/Hz is measured at the receiver input. This is equivalent to a sensitivity of approximately 100 photons, well below the expected signal from the quantum vacuum photons

Characterization of a low noise microwave receiver for the detection of vacuum photons

In this work we present measurements of the sensitivity of a low noise microwave receiver developed with the aim to detect a feeble quantum electrodynamics effect known as dynamical Casimir effect. We study the performance of the receiver when it is connected to a transmission line ending with an antenna coupled to a resonant microwave cavity. The noise temperature of the receiver is measured with the method of the variable temperature load resistor. The noise generated by the cavity is measured in a similar way. An equivalent input noise of (2.0 ± 0.02)x10^22 W/Hz is measured at the receiver input. This is equivalent to a sensitivity of approximately 100 photons, well below the expected signal from the quantum vacuum photons

Evaluation of helical tomotherapy in the treatment of high-grade gliomas near critical structures

Background. Our purpose was to investigate the role of helical tomotherapy using a simultaneous integrated boost technique for the treatment of high-grade gliomas near intracranial critical structures. Methods and materials. Of 27 patients treated with helical tomotherapy, 11 were eligible. Only patients whose tumors were within 0.5 cm of the optic chiasm, the optic nerve or the brainstem were included. The therapeutic approach was a simultaneous integrated boost, prescribing 66 and 60 Gy to the PTV1 and PTV2, respectively, in 30 fractions. All patients received concomitant temozolomide at a dose of 75 mg/m2 daily during radiation therapy. Results. Of the 11 patients considered, 3 patients (27%) died after 4 months from the completion of the combined treatment. Three patients (27%) presented local progression, and the median time to disease progression was 6 months (range, 1-12). Five patients (45%), at the time of this evaluation, did not have signs or symptoms of recurrence or progression of the disease. Acute toxicity, evaluated during radiochemotherapy, was minimal, with all patients experiencing RTOG grade 0 and grade 1 toxicity. Conclusions. Helical tomotherapy proved to be an effective and safe treatment modality, with an improvement of accuracy in delivery of highdose radiotherapy despite the presence of nearby critical structures. © Il Pensiero Scientifico Editore

Semiconductor microwave mirror for a measurement of the dynamical Casimir effect

According to QED a metallic mirror set in motion in quantum vacuum gives rise to \u201cdissipated\u201d energy in the form of real photons. This phenomenon, called dynamical Casimir effect, has never been observed due to unsolved technical difficulties: in order to obtain an experimentally measurable number of photons from vacuum fluctuations a reflecting surface has in fact to vibrate at very high frequencies 109 Hz. As these frequencies are too high to be achieved with a purely mechanical oscillation, our idea is to switch an effective microwave mirror on and off at very short intervals of time changing the reflectivity of a semiconductor layer by shining a pulsed laser beam on its surface. The first step to study the feasibility of this technique is to show that a semiconductor slab when illuminated by a laser behaves indeed as a metal. This article presents the measurements that confirm this demand, obtained by uniformly illuminating large (several square centimeters) surfaces of silicon and GaAs

Resonance frequency shift in a cavity with a thin conducting film near a conducting wall

We show that a very thin conducting film (whose thickness can be much smaller than the skin depth), placed nearby a wall of an electromagnetic cavity, can produce the same shift of the resonance frequency as a bulk conducting slab, provided the displacement of the film from the wall is much bigger than the skin depth. We derive a simple analytical formula for the frequency shift and compare it with exact numerical calculations and experimental dat