Optimizing floating guard ring designs for FASPAX N-in-P silicon sensors

FASPAX (Fermi-Argonne Semiconducting Pixel Array X-ray detector) is being developed as a fast integrating area detector with wide dynamic range for time resolved applications at the upgraded Advanced Photon Source (APS.) A burst mode detector with intended \mbox{13 MHz} image rate, FASPAX will also incorporate a novel integration circuit to achieve wide dynamic range, from single photon sensitivity to $10^{\text{5}}$ x-rays/pixel/pulse. To achieve these ambitious goals, a novel silicon sensor design is required. This paper will detail early design of the FASPAX sensor. Results from TCAD optimization studies, and characterization of prototype sensors will be presented.Comment: IEEE NSS-MIC 2015 Conference recor

A Study of Monolithic CMOS Pixel Sensors Back-thinning and their Application for a Pixel Beam Telescope

This paper reports results on a detailed study of charge collection and signal-to-noise performance of CMOS monolithic pixel sensors before and after back-thinning and their application in a pixel beam telescope for the ALS 1.5 GeV $e^-$ beam test facility.Comment: 6 pages, one figure, to appear on the proceedings of the the Sixth International "Hiroshima" Symposium on the Development and Application of Semiconductor Tracking Detectors, Carmel, CA, September, 200

Current mode monolithic active pixel sensor with correlated double sampling for charged particle detection

A monolithic active pixel sensor operating in current mode for charged particle detection is described. The sensing element in each pixel is an n-well/p-sub diode with a PMOS transistor integrated in an n-well. The drop of the n-well potential from the collection of charge modulates the transistor channel current. Each pixel features two current mode memory cells. The subtraction of distant-in-time samples frees the signal of fixed pattern noise (FPN) and of the correlated low-frequency temporal noise components, resulting in extraction of the particle footprint. The subtraction circuits are placed at each column end. A transimpedance amplifier, integrating in sequence two current samples and subtracting the results in an arithmetic operation, was adopted. The integrated version of the transimpedance amplifier, designed with a maximized conversion gain, is burdened by a risk of an early saturation, imperiling its operation, if the dispersions of the dc current component are too big. The degree of dispersions could not be estimated during the design. Some number of columns is available as a backup with the direct current readout. An external realization of the subtracting circuit, based on the same principle, is used to process direct output columns. The concept of the data acquisition setup developed, the tested performance of an array of cells, and the processing circuitry are described

Kinetics of cold crystallization in two liquid crystalline fluorinated homologues exhibiting the vitrified smectic CA∗{C_{A}}^{*} phase

Dielectric relaxation processes in the supercooled antiferroelectric smectic ${C_{A}}^{*}$ phase and crystallization kinetics of two chiral fluorinated 5HF6 and 6HF6 compounds from the same homologous series are investigated. Fragility parameters are determined from the relaxation time of the α-process, including $\tau_{HN}$ from the Havriliak-Negami formula and $\tau_{peak}$ denoting the position of the absorption peak. The coupling coefficient $\xi$ between the characteristic time of isothermal cold crystallization and relaxation time of the α-process is obtained. Despite similar values of the fragility index, the even 6HF6 homologue undergoes cold crystallization much faster than the odd 5HF6 homologue, with significantly different $\xi$ coefficients. Influence of the relaxation time of the $P_{H}$ process (anti-phase phason) in the smectic ${C_{A}}^{*}$ phase on the crystallization kinetics is presumed

Brain perfusion evaluated by perfusion-weighted magnetic resonance imaging before and after stenting internal carotid artery stenosis in asymptomatic and symptomatic patients

Purpose To evaluate the brain perfusion with MRI perfusion weighted imaging (PWI) before and after ICA stenting in asymptomatic and symptomatic patients. Materials and methods PWI was performed 3–21 days before and 3 days after ICA stenting in 31 asymptomatic patients with ICA >70% stenosis – Group I, and in 14 symptomatic patients with ICA >50% stenosis – Group II. PWI was evaluated qualitatively and quantitatively in 5 cerebral territories with: mean transit time (MTT), cerebral blood volume (CBV) and cerebral blood flow (CBF). Mean values of perfusion parameters were measured before and after stenting ΔMTT, ΔCBV, ΔCBF were calculated as subtraction of after-treatment values from those before treatment. Results In qualitative evaluation after ICA stenting perfusion was normalized in 21 patients (80.8%) in Group I and in 8 patients (80%) in Group II. In quantitative estimation MTT decreased significantly after CAS on stented side vs. non-stented side in all examined patients regardless of the group, p<0.05. MTT decreased more in Group II than in Group I in all territories (p<0.05) with the exception of temporal lobe. CBV and CBF have shown insignificant differences. Conclusions 1.In MRI the most useful parameters to assess brain perfusion are MTT and ΔMTT: regardless whether patients are asymptomatic or symptomatic.2.There were no significant differences in CBV and CBF after stenting in both groups of patients.3.The positive effect of ICA stenting measured with decrease of MTT, CBV values and increase of CBF value is more prominent in symptomatic patients

Monolithic Active Pixel Matrix with Binary Counters (MAMBO) ASIC

Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12 keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between the detector and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab

Monolithic Pixel Sensors in Deep-Submicron SOI Technology with Analog and Digital Pixels

This paper presents the design and test results of a prototype monolithic pixel sensor manufactured in deep-submicron fully-depleted Silicon-On-Insulator (SOI) CMOS technology. In the SOI technology, a thin layer of integrated electronics is insulated from a (high-resistivity) silicon substrate by a buried oxide. Vias etched through the oxide allow to contact the substrate from the electronics layer, so that pixel implants can be created and a reverse bias can be applied. The prototype chip, manufactured in OKI 0.15 micron SOI process, features both analog and digital pixels on a 10 micron pitch. Results of tests performed with infrared laser and 1.35 GeV electrons and a first assessment of the effect of ionising and non-ionising doses are discussed.Comment: 5 pages, 7 figures, submitted to Nuclear Instruments and Methods