Search results for "Multiplier"
showing 10 items of 338 documents
Next generation of the Albira small animal PET based on high density SiPM arrays
2015
A new design of the small animal PET Albira system which detectors are based on arrays of SiPMs and monolithic LYSO scintillator is presented here. The system is made out of 3 rings of 8 detectors each, resulting on an axial and transaxial FOVs of 148 and 80 mm, respectively. The scanner is thermally stabilized using air-cooling. Working temperatures around 22–25°C are reached with individual detector variations around 0.2°C minimizing dark count rates and gain drifts. One of the most significant improvements of the current system is the accurate photon impact determination within the crystal volume, specially its depth of interaction. This allows the calculation of the true line of respons…
Cosmic ray effect on the X-ray Trigger Telescope of UFFO/Lomonosov using YSO scintillation crystal array in space
2017
UFFO Burst Alert and Trigger telescope (UBAT) is the X-ray trigger telescope of UFFO/Lomonosov to localize X-ray source with coded mask method and X-ray detector. Its X-ray detector is made up of 36 8×8 pixels Yttrium OxyorthoSilicate (Y2SiO5:Ce, YSO) scintillation crystal arrays and 36 64-channel Multi-Anode PhotoMultiplier Tubes (MAPMTs) for space mission. Its effective detection area is 161cm2 and energy range is several keV to 150 keV. It was successfully launched in April 28, 2016. In several calibration run, we got several X-ray background data. We already knew X-ray background flux is 2-3 counts/cm2/sec in space. However our X-ray background data shows approximately 7-8 times higher …
Existence and orbital stability of standing waves to nonlinear Schr��dinger system with partial confinement
2018
We are concerned with the existence of solutions to the following nonlinear Schr\"odinger system in $\mathbb{R}^3$: \begin{equation*} \left\{ \begin{aligned} -\Delta u_1 + (x_1^2+x_2^2)u_1&= \lambda_1 u_1 + \mu_1 |u_1|^{p_1 -2}u_1 + \beta r_1|u_1|^{r_1-2}u_1|u_2|^{r_2}, \\ -\Delta u_2 + (x_1^2+x_2^2)u_2&= \lambda_2 u_2 + \mu_2 |u_2|^{p_2 -2}u_2 +\beta r_2 |u_1|^{r_1}|u_2|^{r_2 -2}u_2, \end{aligned} \right. \end{equation*} under the constraint \begin{align*} \int_{\mathbb{R}^3}|u_1|^2 \, dx = a_1>0,\quad \int_{\mathbb{R}^3}|u_2|^2 \, dx = a_2>0, \end{align*} where $\mu_1, \mu_2, \beta >0, 2 1, r_1 + r_2 < \frac{10}{3}$. In the system, the parameters $\lambda_1, \lambda_2 \in \R$ are unknown …
Position sensitive photosensors based on SiPM arrays
2014
High-resolution multichannel Time-to-Digital Converter core implemented in FPGA for ToF measurements in SiPM-PET
2013
In this contribution, Coincidence Resolving Time (CRT) results with the developed multichannel FPGA-TDC are showed as a function of different configurations for both, the sensor bias voltage and the digitizer threshold. The dependence of the CRT with the sensor matrix temperature, the amount of SiPM active area and the crystal type are also analyzed. Preliminary measurements carried out with a crystal array of 2 mm pixel size and 10 mm height have shown time resolutions for the entire 144 SiPM two-detectors ensemble as good as 800 ps.
A thermodynamical model of inhomogeneous superfluid turbulence
2007
In this paper we perform a thermodynamical derivation of a nonlinear hydrodynamical model of inhomogeneous superfluid turbulence. The theory chooses as fundamental fields the density, the velocity, the energy density, the heat flux and the averaged vortex line length per unit volume. The restrictions on the constitutive quantities are derived from the entropy principle, using the Liu method of Lagrange multipliers. The mathematical and physical consequences deduced by the theory are analyzed both in the linear and in the nonlinear regime. Field equations are written and the wave propagation is studied with the aim to describe the mutual interactions between the second sound and the vortex t…
Preliminary radiation hardness tests of single photon Si detectors
2010
Single photon Si detectors were fabricated by STMicroelectronics and fully characterized in standard operation conditions and after irradiations. Both single cells and arrays, of dimensions ranging from 5x5 up to 64x64, were electrically tested. The devices operation was studied as a function of the temperature from -25 degrees C to 65 degrees C varying the voltage over breakdown, from 5% up to 20% of the breakdown voltage before and after irradiation using both light ions, 10 MeV B ions to doses in the range 3x10(7)-5x10(10) cm(-2), and X-rays irradiations in the range 0.5-20 krad(Si). Optical characterization was performed using a laser at 659 nm and opportunely chosen filters to vary the…
A Lagrange Multiplier Based Domain Decomposition Method for the Solution of a Wave Problem with Discontinuous Coefficients
2008
In this paper we consider the numerical solution of a linear wave equation with discontinuous coefficients. We divide the computational domain into two subdomains and use explicit time difference scheme along with piecewise linear finite element approximations on semimatching grids. We apply boundary supported Lagrange multiplier method to match the solution on the interface between subdomains. The resulting system of linear equations of the “saddle-point” type is solved efficiently by a conjugate gradient method.
A large-area scintillating fibre detector for relativistic heavy ions
1998
Abstract A scintillating fibre detector for relativistic heavy ions with an active area of 50 × 50 cm 2 has been developed and was tested with various ion beams (1 ≤ Z ≤ 92). At count rates of up to 10 5 particles/s, the position resolution was found to be determined by the fibre width of 1 mm; depending on the nuclear charge of the beam, efficiencies between 89% and 100% and time resolutions between 800 and 200 ps (FWHM) were obtained.
An enhanced, near-term HCPB design as driver blanket for the EU DEMO
2019
The Helium Cooled Pebble Bed (HCPB) breeding blanket is a candidate as driver blanket for the EU DEMO. The reference design of the HCPB is based on a cooling plate “sandwich” arrangement built in Multi-Module Segments. This architecture significantly improved the tritium breeding performance (TBR = 1.15) and the plant circulating power (≈130 MW) compared to the former ITER-like “beer-box”-like design (TBR<1.10, plant circulating power>200 MW). However, several issues remain with this design, in which (1) the still large power required per He circulator (beyond the state-of-the-art for these components) and (2) the large tritium inventory foreseen in Be have been identified as the most…