53756653
Redundancy or GaAs? Two different approaches to solve the problem of SEU (Single Event Upset) in a digital optical link
The fast digital optical links for the ATLAS Liquid Argon Calorimeter must survive in a high radiation environment with a total fluence of 3x10 neutrons (1MeV Si)/cm and 10 kGy (Si). The links based on Agilent Technologies Glink serializer/deserializer set, show a total dose radiation resistance to neutrons and gammas that would allow for 10 years of operation in the ATLAS detector. We have observed, however, an unacceptable rate of single event upsets (SEU) due to neutrons interacting in the silicon-based serializer. In order to solve this problem, we have developed two link systems. The first one, Dual-Glink, is based on a principle of redundancy: data are sent on two independent links. On the reception side, data are analyzed and error recovery is performed without dead time. The second solution uses a GaAs serializer/deserializer set from TriQuint. We observe a very small number of SEU’s. In addition, high speed of 2.5 Gb/s allows for transmission of the data twice during one event period and for error recovery. The design of the 3 types of links, their performance in the laboratory and the results of the radiation tests are presented for all systems.
18930090
Installation and Commissioning of the ATLAS LAr Readout Electronics
The Liquid Argon Calorimeter (LAr) is a subsystem in the ATLAS experiment which is being assembled at the Large Hadron Collider (LHC) at CERN. The readout electronics system for the LAr is discussed here. The front‐end of the readout will work in radiation environment. This special requirement has led to the development of a large number of rad‐hard ASICs. The back‐end of the readout employs DSPs to process data to reduce transmission bandwidth. The installation and commissioning of this readout is also discussed here.
18954058
Quality Control of Optical Transmitters for the ATLAS Liquid Argon Calorimeter
A quality control test is performed on nearly 2000 custom optical transmitters for use in the Liquid Argon Calorimeter of the ATLAS detector. More than 90% of these optical transmitters passed the test and have been installed in the calorimeter readout system. The acceptance criteria, measurement procedure, and results of the quality control test are presented in this note.
17189846
A Serializer ASIC at 5 Gbps for Detector Front-end Electronics Readout
Optical data links are used in detector front-end electronics readout systems of experiments in the Tevatron and the LHC. Optical links in high energy particle physics experiments usually have special requirements such as radiation tolerance, ultra high reliability and low power dissipation. These requirements are often not met by commercial components which are designed for applications in non-radiation, accessible (for maintenance) environment, and for multi-vendor systems so the parts must comply with certain standards. Future HEP experiments such as the upgrades for the sLHC call for optical links with ultra high data bandwidth, higher radiation tolerance and ultra low power dissipation. To meet these challenges and in particular those in the upgrade for the ATLAS Liquid Argon Calorimeter readout that calls for an optical link system of 100 Gbps for each front-end board, we adopted a full custom front-end electronics system design based on application specific integrated circuits. Reported here are the development and test results of two circuits: a 5 Gbps serializer and a 5 GHz phase locked loop, and a block diagram design for the 100 Gbps optical link.
55746504
The versatile link, a common project for super-LHC
A common project to develop a bi-directional, radiation tolerant, high speed (4.8 Gb/s) optical link for future high energy physics experiments is described. Due to be completed in 2012, it targets the upgrade programs of detectors installed at CERN's Large Hadron Collider (LHC). The development of radiation and magnetic field tolerant opto-electronic devices, fibre and connectors is described. Both Single-Mode and Multi-Mode versions of the system operating respectively at 850 nm and 1310 nm wavelength are proposed. First results at component and system level are presented, based mostly on commercially available devices.
120914328
The 120Gbps VCSEL Array Based Optical Transmitter (ATx) development for the High-Luminosity LHC (HL-LHC) experiments
The integration of a Verticle Cavity Surface-Emitting Laser (VCSEL) array and a driving Application-Specific Integrated Circuit (ASIC) in a custom optical array transmitter module (ATx) for operation in the detector front-end is constructed, assembled and tested. The ATx provides 12 parallel channels with each channel operating at 10 Gbps. The optical transmitter eye diagram passes the eye mask and the bit-error rate (BER) less than 10(-12) transmission is achieved at 10 Gbps/ch. The overall insertion loss including the radiation induced attenuation is sufficiently low to meet the proposed link budget requirement.
2486417
Precision test of mass-ratio variations with lattice-confined ultracold molecules.
We propose a precision measurement of time variations of the proton-electron mass ratio using ultracold molecules in an optical lattice. Vibrational energy intervals are sensitive to changes of the mass ratio. In contrast to measurements that use hyperfine-interval-based atomic clocks, the scheme discussed here is model independent and does not require separation of time variations of different physical constants. The possibility of applying the zero-differential-Stark-shift optical lattice technique is explored to measure vibrational transitions at high accuracy.
20964607
Human breath analysis via cavity-enhanced optical frequency comb spectroscopy
To date, researchers have identified over 1000 different compounds contained in human breath. These molecules have both endogenous and exogenous origins and provide information about physiological processes occurring in the body as well as environment-related ingestion or absorption of contaminants1,2. While the presence and concentration of many of these molecules are poorly understood, many 'biomarker' molecules have been correlated to specific diseases and metabolic processes. Such correlations can result in non-invasive methods of health screening for a wide variety of medical conditions. In this article we present human breath analysis using an optical-frequency-comb-based trace detection system with excellent performance in all criteria: detection sensitivity, ability to identify and distinguish a large number of biomarkers, and measurement time. We demonstrate a minimum detectable absorption of 8 x 10-10 cm-1, a spectral resolution of 800 MHz, and 200 nm of spectral coverage from 1.5 to 1.7 micron where strong and unique molecular fingerprints exist for many biomarkers. We present a series of breath measurements including stable isotope ratios of CO2, breath concentrations of CO, and the presence of trace concentrations of NH3 in high concentrations of H2O.
124924859
Direct Observation of SU(N) Orbital Magnetism
8781619
Control of four-level quantum coherence via discrete spectral shaping of an optical frequency comb.
We present experiments demonstrating high-resolution and wide-bandwidth coherent control of a four-level atomic system in a diamond configuration. A femtosecond frequency comb is used to excite a specific pair of two-photon transitions in cold 87Rb. The optical-phase-sensitive response of the closed-loop diamond system is studied by controlling the phase of the comb modes with a pulse shaper. Finally, the pulse shape is optimized resulting in a 256% increase in the two-photon transition rate by forcing constructive interference between the mode pairs detuned from an intermediate resonance.
25651519
New limits on coupling of fundamental constants to gravity using 87Sr optical lattice clocks.
The 1S0-3P0 clock transition frequency nuSr in neutral 87Sr has been measured relative to the Cs standard by three independent laboratories in Boulder, Paris, and Tokyo over the last three years. The agreement on the 1 x 10(-15) level makes nuSr the best agreed-upon optical atomic frequency. We combine periodic variations in the 87Sr clock frequency with 199Hg+ and H-maser data to test local position invariance by obtaining the strongest limits to date on gravitational-coupling coefficients for the fine-structure constant alpha, electron-proton mass ratio mu, and light quark mass. Furthermore, after 199Hg+, 171Yb+, and H, we add 87Sr as the fourth optical atomic clock species to enhance constraints on yearly drifts of alpha and mu.