Real-time SiPM gain variation compensation system using count rate measurements

The anti-jamming antenna is one of the most efficient ways to resist the adversary effect of the interference signal in GNSS positioning. Most anti-jamming antennas can adaptively adjust the radiation figure of the antenna to minimize the interference impact. A side effect of changing the radiation figure is that the antenna phase center (APC) is also changed accordingly. Meanwhile, a stable phase center is a prerequisite for high precision GNSS positioning, thus the anti-jamming and high-precision becomes a dilemma for the GNSS antenna design. This study proposed an efficient antenna phase center variation (PCV) compensation algorithm for the anti-jamming antennas which enables real-time high-precision applications with the anti-jamming antennas. The performance of the algorithm is evaluated with the short baseline tests, and the results indicate that the proposed algorithm can reduce the carrier phase residuals by compensation of the anti-jamming antenna PCV and consequently, the 3D root mean squares (RMS) of real-time kinematic (RTK) positioning in two experiments is improved by 42.3% and 9.7% respectively. After PCV correction, the RTK positioning with the anti-jamming antennas achieves better than 4 cm accuracy.

In the search for ‘cold fusion’ reactions in solids loaded with deuterium atoms at high concentration, ion implantation has been used as a means to reach the required high deuterium concentration in the lattice. In the present investigations, 300 eV to 6 keV D+ ions were injected into 3 μm thick titanium foils at room temperature and at 140 K. The protons from the D(d,p)T reaction were monitored using a solid state detector with a large solid angle, both during and after implantation. After implantation of deuterium in the titanium foil up to saturation, i.e. with about 1.8 deuterium atoms per titanium atom at room temperature, the possible fusion reaction rate at equilibrium was determined over a period of 65 h. The measured count rate was within the limits of the natural background, and an upper limit of 1 × 10−23 per deuterium pair per second was established. During implantation of deuterium at energies between 3 and 6 keV, the count rate is dominated by reactions of the incident energetic deuterons with deuterons already implanted in the foil. The D-D reaction cross-sections, evaluated at 140 K, follow closely those obtained by extrapolation of the Gamow function to low energies. During implantation of 300 eV D+ ions, no counts from the D(d,p)T reactions were monitored, showing that even under extreme conditions of non-equilibrium the possible ‘cold fusion’ reaction rate is smaller than the background count rate.

Passive gamma analysis of the boiling-water-reactor assemblies

This paper describes the results of calibration measurements for a Bonner sphere spectrometer (BSS) with 3He proportional counter performed in quasi-monoenergetic neutron fields at the Research Center for Nuclear Physics (RCNP) at the University of Osaka, Japan. Using 246 MeV and 389 MeV proton beams, neutron fields with nominal peak energies of 244 MeV and 387 MeV were generated via 7Li(p,n)7Be reactions. At high energies, the neutron spectra were measured by means of the time-of-flight (TOF) method. The low-energy part of the neutron spectra were determined by BSS measurements down to thermal energies using the MSANDB unfolding code and three different sets of response functions. These were obtained by means of Monte Carlo (MC) calculations including various codes and intra-nuclear cascade (INC) models. Unfolded BSS fluence rates were additionally confirmed by GEANT4 calculations. For calibration of the BSS, measured count rates were corrected for low-energy contributions and compared with count rates calculated using TOF data and various response functions. In addition, measured response values were compared with mono-energetic response calculations, and best agreement was found with GEANT4 results using the Bertini INC model.

Accelerator-based neutron fields for the mock up of workplace spectra – first experimental results and comparison with calculations

The effects of collimator geometry and self-absorption on in-situ mass diffusion measurements

Analysis of scattered bremsstrahlung radiation in the vicinity of medical linear accelerator by Monte Carlo simulations.

Positron Emission Tomography (PET) image quality deteriorates as the object size increases owing to increased detection of scattered and random events. The characterization of the scatter component in small animal PET imaging has received little attention owing to the small scatter fraction when imaging rodents. The purpose of this study is first to design and fabricate a dedicated cone-shaped phantom which can be used for measurement of object size dependent SF and noise equivalent count (NEC) rates and second, to evaluate those parameters for two small animal PET scanners, namely the X-PET™ and LabPET™-8 as function of radial offset, object size and lower energy threshold. Both scanners were modeled as realistically as possible using GATE Monte Carlo simulation platform. The simulation models were validated against experimental measurements in terms of sensitivity, SF and noise equivalent count rate (NECR). The dedicated phantom was designed and fabricated in-house using high-density polyethylene. The optimized dimensions of the cone-shaped phantom are 150 mm (length), 20 mm (minimum diameter), 70 mm (maximum diameter) and taper angle of 9°.The relative difference between simulated and experimental results for the LabPET™-8 scanner varied between 0.66% and 10% except for few results where it was below 16%. Depending on the radial offset from the axial centre for a central field of view (3–6 cm diameter), the SF for the cone-shaped phantom varied from 26.3 to 18.2% (X-PET™); 34.4 to 26.9% (LabPET™-8), 18.6 to 13.1% (X-PET™); 19.1 to 17.0% (LabPET™-8); 10.1 to 7.6% (X-PET™) and 9.1 to 7.3% (LabPET™-8) for lower energy thresholds of 250, 350 and 425 keV, respectively. The SF increases as the radial offset decreases, lower energy threshold (LET) decreases and object size increases. The SF values are higher for the LabPET™-8 compared to the X-PET™. The NECR increases as the radial offset increases and object size decreases. Maximum NECR was obtained at a LET of 350 keV for LabPET™-8 whereas 250 keV for X-PET™. High correlation coefficients (R2) for SF and NECR were observed between the cone-shaped phantom and an equivalent volume cylindrical (EVC) phantom for the three considered axial fields-of-view. A single cone-shaped phantom enables the assessment of effects of three factors, namely radial offset, energy threshold and object size on small animal PET imaging characteristics like SF and NECR. Hence, a cone-shaped phantom may be more suited for evaluation of object size-dependent SF and NECR instead of using various discrete phantoms of different size.

High-speed Nuclear Quality Pulse Height Analyzer for Synchrotron-based Applications J-F. Beche, J. J. Bucher, L. Fabris, V. J. Riot Abstract--A high throughput Pulse Height Analyzer system for synchrotron-based applications requiring high resolution, high processing speed and low dead time has been developed. The system is comprised of a 120ns 12-bit nuclear quality Analog to Digital converter with a self-adaptive fast peak detector- stretcher and a custom-made fast histogramming memory module that records and processes the digitized data. The histogramming module is packaged in a VME or VXI compatible interface. Data is transferred through a fast optical link from the memory interface to a computer. A dedicated data acquisition program matches the hardware characteristics of the histogramming memory module. The data acquisition system allows for two data collection modes: “standard” data acquisition mode where the data is accumulated and read in synchronization with an external trigger and “live” data acquisition mode where the system operates as a standard Pulse Height Analyzer. The acquisition, standard or live, can be performed on several channels simultaneously. A two-channel prototype has been demonstrated at the Stanford Synchrotron Radiation Laboratory accelerator in conjunction with an X-ray Fluorescence Absorption Spectroscopy experiment. A detailed description of the entire system is given and experimental data is shown. I. S UMMARY A fast high resolution and low dead time Pulse Height Analyzer (PHA) system for Synchrotron-based applications has been developed. This module is an addition to and completes the previously designed custom electronics for XAFS applications [1, 2]. The PHA system receives analog information from a low dead time pulse processing front-end section. The low dead time PHA system is comprised of a fast high resolution Analog to Digital Converter (ADC), a fast histogramming memory and a VME or VXI compatible interface. The VME-based system consists of one complete data acquisition channel. The VXI-based PHA system addresses the problem of simultaneous data acquisition from multiple channels. Both systems were tested at the Stanford Synchrotron Radiation Laboratory in conjunction with an X- ray Fluorescence Absorption Spectroscopy experiment. The block diagram of a single acquisition channel is shown in Fig. This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Chemical Science Division of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. J-F Beche, J. J. Bucher, L. Fabris and V. J. Riot are with E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA (telephone: 510- 495-2327, e-mail: JFBeche@lbl.gov). The analog input section is built around a fast self-adaptive peak detector-stretcher described in [1]. The peak detector- stretcher includes all the necessary logic to provide pileup rejection and gating functions. The stretched signal is fed to a commercial ADC chosen to maximize throughput without compromising the differential non-linearity (DNL). This ADC is an 8Msps unit, providing 14 bit of resolution with no missing code over the full temperature range, and with an intrinsic DNL of ½ LSB. In order to improve the DNL (not adequate for nuclear spectroscopy applications), only the first 12 most significant bits are used. A 6-bit sliding scale correction [3] lowers the DNL to less than 1%. Including delays, the conversion time of the ADC is 120ns. The electronic pulse-processing amplifier, in its fastest version, shapes the energy events coming from the detector with a 250ns peaking time fourth-order, pseudo-gaussian shaping function. The conversion time of the ADC does not add to the dead time associated with the pulse-shaping amplifier. Data collection is either gated by an external synchronization signal such as an accelerator beam clock or a precise clock signal to time-stamp the data collection and measure count rates. After an analog to digital conversion has taken place, the ADC board control logic sends a request to the histogramming memory module. When the histogramming memory controller acknowledges the request, it uses the ADC data to increment by one the content of the corresponding address memory location. The entire operation lasts 130ns, which is less than the dead time of the pulse- processing amplifier. Therefore, the histogramming operation does not increase the overall event-by-event processing time of the entire system. The histogramming memory module is packaged in a VME or VXI compatible interface and is built around a dual-port static random access memory. One port is dedicated to data accumulation while the second port is mapped to the VME or VXI address and data buses. The transfer to the computer is controlled by either the synchronization signal in the form of an interrupt signal sent to the VME or VXI controller, or by the computer accessing the memory at regular time intervals. The former corresponds to the “standard” acquisition mode and the latter to the “live” mode. In standard mode the content of the histogramming memory must be erased (zeroed) before collecting any new data set.

In order to improve the machine accuracy,a synthesis modelling method of geometric and thermal error is presented.Machine error distribution law is obtained through the analysis of machine error data at varying temperatures.Based on the different characteristics of geometric error and thermal error,error separation is carried out.Synthesis mathematical model for geometric and thermal error is proposed by using polynomial fitting and linear fitting.Online real-time error compensation is implemented by applying the computer numerical control(CNC) external machine coordinate system shift function and a novel developed synthesis error real-time compensation system.This error compensation method concerns the geometric error and its variations at different temperatures,thus a comprehensive analysis is made on the error and its regularity in the overall temperature rise to the heat steady-state.The inspection certificates that the maximum positioning error in normal temperature is reduced from 44.1 μm to 3.6 μm by applying the error compensation method and real-time compensation system,which is compensated 91.8% compared with no compensation.After the temperature rise,the maximum positioning error in normal temperature is reduced from 26.0 μm to 5.1 μm,which is compensated 80.4% compared with no compensation.The machine accuracy is effectively improved.

We developed a novel real-time motion blur compensation system for the blur caused by high-speed one-dimensional motion between a camera and a target. The system consists of a galvanometer mirror and a high-speed color camera, without the need for any additional sensors. We controlled the galvanometer mirror with continuous back-and-forth oscillating motion synchronized to a high-speed camera. The angular speed of the mirror is given in real time within 10 ms based on the concept of background tracking and rapid raw Bayer block matching. Experiments demonstrated that our system captures motion-invariant images of objects moving at speeds up to 30 km/h.

We report on the high count rate and high frame rate measurements of a prototype IC called FPDR90 dedicated for readout of hybrid pixel semiconductor detectors used for X-ray imaging applications. The FPDR90 is designed in 90 nm CMOS technology and has dimensions of 4 mm × 4 mm. It's main part is a matrix of 40 × 32 pixels with 100 μm × 100 μm pixel size. The chip work in single photon counting mode with two discriminators and two 16-bit ripple counters per pixel. The count rate per pixel depends on the effective CSA feedback resistance and can be set up to 6 Mcps per pixel. The FPDR90 can operate in continuous readout mode, with a zero dead time. Due to the architecture of digital blocks in pixel, one can select the number of readout bits from each counter from 1 to 16 bits. Because in the FPDR90 prototype only one data output is available, the frame rate is 9 kHz and 72 kHz for 16 bits and 1 bit readout from single pixel respectively (with nominal clock frequency of 200 MHz).

This article presents a novel DMD-based adaptive lithography system enabling real-time compensation for substrate deformation during patterning. The system integrates conventional DMD lithography with optical measurement capabilities to quantify substrate deformation and dynamically adjust patterns based on upstream measurements. To achieve high-precision patterning while maintaining real-time operation, we implement oblique scanning for enhanced precision and optimized image processing with parallel computing techniques. Experimental results demonstrate effective compensation for substantial substrate deformations, reducing positional error from ±76.7 μm (∼3σ) to registration precision of ±3.8 μm and stitching precision of ±2.5 μm. This real-time deformation compensation addresses critical challenges in roll-to-roll manufacturing of flexible electronics and wafer-level packaging, where substrate deformation traditionally limits patterning accuracy. The approach enables precise pattern registration on deformable substrates without specialized stitching procedures, offering significant advantages for diverse and complex form factors in next-generation electronic devices.

Design of feedback wavelength demodulation and compensation system for FBG-tuned CW fiber laser

Synchrony – Cyberknife Respiratory Compensation Technology