Investigation into a GPS time pulse radiator for testing time-stamp accuracy of a radio telescope

The MeerKAT radio telescope in South Africa is required to tag the arrival time of a signal to within 10 ns of Coordinated Universal Time (UTC). The telescope has a local atomic clock ensemble and uses satellite based remote clock comparison techniques to compare the telescope time to UTC. The master clock timing edge is distributed to each telescope antenna via an optical fibre precise time transfer. Although the timing accuracy of the telescope time was measured internally by the telescope, there is a need for an independent method to verify how well each antenna and its associated processing stages are aligned to UTC. A portable GNSS time-pulse radiator (GTR) device for testing the time-stamp accuracy was developed. The GTR was calibrated at the National Metrology Institute of South Africa and laboratory characterisation tests measured its RF timing pulse to be 1.32 ± 0.100 µs ahead of the UTC second. The telescope’s time and frequency reference clock ensemble consists of two hydrogen masers, an ultrastable crystal and GPS disciplined Rubidium clocks. During operation, the GTR radiates a broadband GPS time synchronised RF timing signal at a known distance from the telescope antennas and the corresponding timestamps were compared to the expected value. Recent GTR timing tests performed on one of the MeerKAT antennas showed that the telescope’s generated timestamps associated with the GTR’s RF timing signal coincided with the expected delay of approximately 16 ± 0.1 µs measured from an antenna 4.8 km away from the telescope’s master clock transmitter. Ultimately we used the GTR to verify that the telescope time and UTC were aligned to within 100 ns. Future work is planned to improve the profile of the transmitted signal and timing critical hardware in order to reduce the GTR’s error budget

Study of a prototype module of a precision time-of-flight detector for particle identification at low momentum

In this thesis, Time Of internally Reflected Cherenkov light detector (TORCH), proposed for the LHCb Upgrade to perform three-sigma separation between kaon and pion up to 10 GeV/c, was studied. TORCH is designed to add significant particle identification capability to the existing LHCb system based on two gas Ring Imaging Cherenkov detectors. TORCH would be placed at ~10 m from the interaction point, where the flight time difference between a primary pion and kaon is 37.5 ps. TORCH will give a pion-kaon separation of three sigma at 10 GeV/c from the flight time using the Cherenkov photons generated by the charged particle in a 1 cm-thick quartz plate. In order to calculate accurately the flight time in a busy LHCb environment, Cherenkov angle and photon detection time information, as well as the momentum information from the tracking detector are included in the analysis. For the required TORCH performance, the flight time difference must be measured with a resolution of better than 70 ps for a single Cherenkov photon. In order to demonstrate the required performance, the intrinsic time resolution of the photon detector and electronics jitter have been investigated, firstly with commercially available Micro-Channel Plate Photo Multiplier Tubes (MCP-PMT) and electronics, then custom-made Multi-Channel MCP-PMT with custom-made electronics, which are designed for the TORCH R&D. The Multi-Channel MCP-PMT has been developed in collaboration with industry. For the custom electronics, NINO, an ASIC chip developed for the Time of Flight detector of the ALICE experiment was used as well as the HPTDC ASIC chip, which is being used by the ATLAS, CMS and ALICE experiments. Important characteristics such as the linearity and time walk have been carefully analysed and a method to correct biases introduced by those characteristics has been developed. TORCH optics must propagate the Cherenkov photons to the photocathode of the Multichannel MCPMT with minimum loss. On the other hand, spectra of photons reaching the photocathode should not be too wide in order to limit the chromatic error. All the optical components have been tested with a stand-alone system and results are compared with simulation studies. A small scale TORCH prototype has been constructed to test the system with a charged-particle beam and results are being analysed

Engineering evaluations and studies. Volume 3: Exhibit C

High rate multiplexes asymmetry and jitter, data-dependent amplitude variations, and transition density are discussed

Towards Very Large Scale Analog (VLSA): Synthesizable Frequency Generation Circuits.

Driven by advancement in integrated circuit design and fabrication technologies, electronic systems have become ubiquitous. This has been enabled powerful digital design tools that continue to shrink the design cost, time-to-market, and the size of digital circuits. Similarly, the manufacturing cost has been constantly declining for the last four decades due to CMOS scaling. However, analog systems have struggled to keep up with the unprecedented scaling of digital circuits. Even today, the majority of the analog circuit blocks are custom designed, do not scale well, and require long design cycles. This thesis analyzes the factors responsible for the slow scaling of analog blocks, and presents a new design methodology that bridges the gap between traditional custom analog design and the modern digital design. The proposed methodology is utilized in implementation of the frequency generation circuits – traditionally considered analog systems. Prototypes covering two different applications were implemented. The first synthesized all-digital phase-locked loop was designed for 400-460 MHz MedRadio applications and was fabricated in a 65 nm CMOS process. The second prototype is an ultra-low power, near-threshold 187-500 kHz clock generator for energy harvesting/autonomous applications. Finally, a digitally-controlled oscillator frequency resolution enhancement technique is presented which allows reduction of quantization noise in ADPLLs without introducing spurs.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/109027/1/mufaisal_1.pd

High power X-band RF test stand development and high power testing of the CLIC crab cavity

This thesis describes the development and operation of multiple high power X-band RF test facilities for high gradient acceleration and deflecting structures at CERN, as re-quired for the e+ e- collider research programme CLIC (Compact Linear Collider). Signif-icant improvements to the control system and operation of the first test stand, Xbox-1 are implemented. The development of the second X-band test stand at CERN, Xbox-2 is followed from inception to completion. The LLRF (Low Level Radio Frequency) system, interlock system and control algorithms are designed and validated. The third test stand at CERN, Xbox-3 is introduced and designs for the LLRF and control systems are pre-sented. The first of the modulator/klystron units from Toshiba and Scandinova is tested. CLIC will require crab cavities to align the bunches in order to provide effective head-on collisions. An X-band travelling wave cavity using a quasi-TM11 mode for deflection has been designed, manufactured and tested at the Xbox-2 high power test stand. The cavity reached an input power level in excess of 50 MW, at pulse widths of 150 ns with a measured breakdown rate (BDR) of better than 10-5 breakdowns per pulse (BDs/pulse). At the nominal pulse width of 200 ns, the cavity reached an input power level of 43 MW with a BDR of 10-6 BDs/pulse. These parameters are well above the nominal design pa-rameters of an input power of 13.35 MW with a 200 ns pulse length. This work also de-scribes surface field quantities which are important in assessing the expected BDR when designing high gradient structures

In Situ Automatic Analog Circuit Calibration and Optimization

As semiconductor technology scales down, the variations of active/passive device characteristics after fabrication are getting more and more significant. As a result, many circuits need more accuracy margin to meet minimum accuracy specifications over huge process-voltage-temperature (PVT) variations. Although, overdesigning a circuit is sometimes not a feasible option because of excessive accuracy margin that requires high power consumption and large area. Consequently, calibration/tuning circuits that can automatically detect and compensate the variations have been researched for analog circuits to make better trade-offs among accuracy, power consumption, and area. The first part of this dissertation shows that a newly proposed in situ calibration circuit for a current reference can relax the sharp trade-off between the temperature coefficient accuracy and the power consumption of the current reference. Prototype chips fabricated in a 180 nm CMOS technology generate 1 nA and achieve an average temperature coefficient of 289 ppm/°C and an average line sensitivity of 1.4 %/V with no help from a multiple-temperature trimming. Compared with other state-of-the-art current references that do not need a multiple-temperature trimming, the proposed circuit consumes at least 74% less power, while maintaining similar or higher accuracy. The second part of this dissertation proves that a newly proposed multidimensional in situ analog circuit optimization platform can optimize a Tow-Thomas bandpass biquad. Unlike conventional calibration/tuning approaches, which only handle one or two frequency-domain characteristics, the proposed platform optimizes the power consumption, frequency-, and time-domain characteristics of the biquad to make a better trade-off between the accuracy and the power consumption of the biquad. Simulation results show that this platform reduces the gain-bandwidth product of op-amps in the biquad by 80% while reducing the standard deviations of frequency- and time-domain characteristics by 82%. Measurement results of a prototype chip fabricated in a 180 nm CMOS technology also show that this platform can save maximum 71% of the power consumption of the biquad while the biquad maintains its frequency-domain characteristics: Q, ωO and the gain at ωO

Fission studies in inverse kinematics and associated development of new time-of-flight

This work focuses on the proton- and deuteron-induced fission of 181Ta and 208Pb measured in experiments performed at GSI (Helmholtzzentrum für Schwerionenforschung - Darmstadt Alemania) using the inverse kinematics technique. According to this scope, a dedicated experimental setup with high acceptance and efficiency for fission measurements is used. The obtained results allow to improve the knowledge about fission cross sections of relevance for the construction of spallation neutron sources useful in many technology areas. In addition, reaction codes based on models describing the fission process at high excitation energies are also investigated and benchmarked by comparison to our experimental data. The experimental part is completed with the R and D of Resistive Plate Chambers (RPC) for the construction of a time-of-flight detector for the R3B experiment in the forthcoming FAIR facility (Darmstadt)

Proceedings of the Eleventh Annual Precise Time and Time Interval (PTTI) Application and Planning Meeting

Thirty eight papers are presented addressing various aspects of precise time and time interval applications. Areas discussed include: past accomplishments; state of the art systems; new and useful applications, procedures, and techniques; and fruitful directions for research efforts