DFT and BIST of a multichip module for high-energy physics experiments

Engineers at Politecnico di Torino designed a multichip module for high-energy physics experiments conducted on the Large Hadron Collider. An array of these MCMs handles multichannel data acquisition and signal processing. Testing the MCM from board to die level required a combination of DFT strategie

In-system Jitter Measurement Based on Blind Oversampling Data Recovery

The paper describes a novel method for simple estimation of jitter contained in a received digital signal. The main objective of our research was to enable a non-invasive measurement of data link properties during a regular data transmission. To evaluate the signal quality we estimate amount of jitter contained in the received signal by utilizing internal signals of a data recovery circuit. The method is a pure digital algorithm suitable for implementation in any digital integrated circuit (ASIC or FPGA). It is based on a blind-oversampling data recovery circuit which is used in some receivers instead of a traditional PLL-based clock and data recovery (CDR) circuit. Combination of the described jitter measurement block and the data recovery block forms a very efficient input part of the digital receiver. In such configuration it is able to simultaneously perform both data communication (data recovery) and signal quality estimation (jitter measurement). The jitter measurement portion of the receiver requires no special connection of the received data signal. Thus the measured signal is not influenced by the measurement circuitry at all. To verify the method we performed a measurement on a laboratory free-space optics link. Results of the measurement are satisfactory and can be used for on-line channel analysis

Development and analysis of the Software Implemented Fault-Tolerance (SIFT) computer

SIFT (Software Implemented Fault Tolerance) is an experimental, fault-tolerant computer system designed to meet the extreme reliability requirements for safety-critical functions in advanced aircraft. Errors are masked by performing a majority voting operation over the results of identical computations, and faulty processors are removed from service by reassigning computations to the nonfaulty processors. This scheme has been implemented in a special architecture using a set of standard Bendix BDX930 processors, augmented by a special asynchronous-broadcast communication interface that provides direct, processor to processor communication among all processors. Fault isolation is accomplished in hardware; all other fault-tolerance functions, together with scheduling and synchronization are implemented exclusively by executive system software. The system reliability is predicted by a Markov model. Mathematical consistency of the system software with respect to the reliability model has been partially verified, using recently developed tools for machine-aided proof of program correctness

Baseband processor for IEEE 802.11a standard with embedded BIST

In this paper results of an IEEE 802.11a compliant low-power baseband processor implementation are presented. The detailed structure of the baseband processor and its constituent blocks is given. A design for testability strategy based on Built-In Self-Test (BIST) is proposed. Finally implementational results and power estimation are reported

Resonance ionization spectroscopy of thorium isotopes - towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of Th-229

In-source resonance ionization spectroscopy was used to identify an efficient and selective three step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in preparation of laser spectroscopic investigations for an identification of the low-lying Th-229m isomer predicted at 7.6 +- 0.5 eV above the nuclear ground state. Using a sample of Th-232, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing states were identified. Level energies were determined with an accuracy of 0.06 cm-1 for intermediate and 0.15 cm-1 for auto-ionizing states. Using different excitation pathways an assignment of total angular momenta for several energy levels was possible. One particularly efficient ionization scheme of thorium, exhibiting saturation in all three optical transitions, was studied in detail. For all three levels in this scheme, the isotope shifts of the isotopes Th-228, Th-229, and Th-230 relative to Th-232 were measured. An overall efficiency including ionization, transport and detection of 0.6 was determined, which was predominantly limited by the transmission of the mass spectrometer ion optics

An On-Chip Delay Measurement Technique for Small-Delay Defect Detection using Signature Registers

This paper presents a delay measurement technique using signature analysis, and a scan design for the proposed delay measurement technique to detect small-delay defects. The proposed measurement technique measures the delay of the explicitly sensitized paths with the resolution of the on-chip variable clock Generator. The proposed scan design realizes complete on-chip delay measurement in short measurement time using the proposed delay measurement technique and extra latches for storing the test vectors. The evaluation with Rohm 0.18- m process shows that the measurement time is 67.8% reduced compared with that of the delay measurement with standard scan design on average. The area overhead is 23.4% larger than that of the delay measurement architecture using standard scan design, and the difference of the area overhead between enhanced scan design and the proposed method is 7.4% on average. The data volume is 2.2 times of that of test set for normal testing on average

Overview of the Experimental Physics and Industrial Control System (EPICS) Channel Archiver

The Channel Archiver has been operational for more than two years at Los Alamos National Laboratory and other sites. This paper introduces the available components (data sampling engine, viewers, scripting interface, HTTP/CGI integration and data management), presents updated performance measurements and reviews operational experience with the Channel Archiver.Comment: 3 pages, 1 figure, 8th International Conference on Accelerator and Large Experimental Physics Control Systems (PSN THAP019), San Jose, CA, USA, November 27-3

Precision spectroscopy by photon-recoil signal amplification

Precision spectroscopy of atomic and molecular ions offers a window to new physics, but is typically limited to species with a cycling transition for laser cooling and detection. Quantum logic spectroscopy has overcome this limitation for species with long-lived excited states. Here, we extend quantum logic spectroscopy to fast, dipole-allowed transitions and apply it to perform an absolute frequency measurement. We detect the absorption of photons by the spectroscopically investigated ion through the photon recoil imparted on a co-trapped ion of a different species, on which we can perform efficient quantum logic detection techniques. This amplifies the recoil signal from a few absorbed photons to thousands of fluorescence photons. We resolve the line center of a dipole-allowed transition in 40Ca+ to 1/300 of its observed linewidth, rendering this measurement one of the most accurate of a broad transition. The simplicity and versatility of this approach enables spectroscopy of many previously inaccessible species.Comment: 25 pages, 6 figures, 1 table, updated supplementary information, fixed typo

Quantum state preparation and control of single molecular ions

Preparing molecules at rest and in a highly pure quantum state is a long standing dream in chemistry and physics, so far achieved only for a select set of molecules in dedicated experimental setups. Here, a quantum-limited combination of mass spectrometry and Raman spectroscopy is proposed that should be applicable to a wide range of molecular ions. Excitation of electrons in the molecule followed by uncontrolled decay and branching into several lower energy states is avoided. Instead, the molecule is always connected to rotational states within the electronic and vibrational ground-state manifold, while a co-trapped atomic ion provides efficient entropy removal and allows for extraction of information on the molecule. The outlined techniques might enable preparation, manipulation and measurement of a large multitude of molecular ion species with the same instrument, with applications including, but not limited to, precise determination of molecular properties and fundamental tests of physics.Comment: 12 pages, 2 figures, reformatted for resubmissio