Query: Measuring Signal Generator Response Through an ADC Evaluation Board

Candidate papers:

abstract: Many semiconductor industries use Automated Test Equipment (ATE) which comprises of linear and mixed signals instruments. External Signal generators are usually not associated to the equipment's calibration or checker routine. This research introduces a method of testing the functionality of the signal generators by establishing a signal generator checker for automated test equipment using Analog to Digital Converter (ADC) evaluation board and Field Programmable Gate Array (FPGA) capture board. This setup will enable the system to focus on fundamental frequency and amplitude level of the signal generator. A Visual Basic Application (VBA) program was created to control the desired frequency and amplitude level of the signal generator. The FPGA evaluates the digital signal and graphically presents it in a system data platform software. In result, the graphical output displays the quality of the signal generator through the full scale fundamental frequency and amplitude levels. The common problems encountered using ATEs, namely; loosed RF cable, incorrect RF cable connections on ATE configuration, and noisy signal generators can be detected. This research is precedent to a more intelligent and complex signal generator checker to ensure signal integrity.
author_names: Limuel R Landicho

Irvin B Garcia

Glenn N Ortiz

Mark Joseph B Enojas
title: Measuring Signal Generator Response Through An Adc Evaluation Board
year: 2020

abstract: Instruction in the theory and operation of analog electronic circuits remains an essential element of contemporary electrical engineering curricula. While computer based simulation of these circuits is extremely helpful to mastery of essential topics, hardware implementation of these circuits in the undergraduate electronics laboratory best reinforces theoretical explanations and solidifies understanding. However, hardware reinforcement of more advanced topics such as component dependent frequency response, feedback and pole compensation is more difficult to achieve. Hardware circuits implemented by students will inevitably possess anomalies and errors which thwart the achievement of a laboratory's teaching objectives. After some years of development, we have found that a prepared custom differential amplifier presented on small custom printed circuit board (PCB) can greatly improve the undergraduate laboratory experience with advanced analog amplifier circuits. This circuit performs in a predictable, repeatable manner since correct component connections and biasing has been established and parasitic circuit elements are fixed. Components within the circuit remain accessible to test equipment so students may verify circuit condition. External components chosen by the student can be easily added to illustrate important behaviors. Furthermore, additional stages can be added to this circuit, presenting additional opportunities for student design. We fabricate these circuits in sufficient numbers that inevitable student mis application of these PCBs is easily remedied. This paper discusses the objectives of instruction, theory of operation, implementation details, robustness and student experience related to this circuit. Sufficient detail is provided so that interested faculty may easily reproduce our design. Introduction Instruction in the theory and operation of analog electronic circuits remains an essential element of contemporary electrical engineering curricula. While computer based simulation of these circuits is extremely helpful to mastery of essential topics, hardware implementation of these circuits in the undergraduate electronics laboratory best reinforces theoretical explanations and solidifies understanding. However, hardware reinforcement of more advanced topics such as component dependent frequency response, feedback and pole compensation is more difficult to achieve. Hardware circuits P ge 1.32.1 Proceedings of the 2005 American Society for Engineering Education Annual Conference and Exposition Copyright (c) 2005, American Society for Engineering Education implemented by students will inevitably possess anomalies and errors which thwart the achievement of a laboratory's teaching objectives. After some years of development, we have found that a prepared custom differential amplifier presented on small custom printed circuit board (PCB) can greatly improve the undergraduate laboratory experience with advanced analog amplifier circuit concepts. In this paper, I present the pedagogical framework in which this amplifier is presented, details of the amplifier's design and operation, as well as information relevant to its fabrication and implementation. Pedagogical Framework The laboratory exercise which employs our printed circuit board (PCB) based amplifier is one of eight executed in our two semester required course sequence in electronics. Laboratory exercises are integrated with lecture and classroom exercises with the same faculty member responsible for both forms of instruction. Laboratory exercises throughout our curriculum follow a cycle of theoretical analysis or design followed by computer based simulation which are subsequently compared with hardware circuit performance. The first course in the electronics sequence, Electronics I El Engr 321 covers semiconductor physics and the theory of operation of the junction diode, bipolar junction transistor (BJT) and metal oxide semiconductor field effect transistor (MOSFET) Circuits involving small numbers of these active devices are used to illustrate their operation and practical importance. Complementary hardware laboratory exercises reinforce the concepts of diode and transistor biasing as well as small and large signal operation. The second electronics course, Electronics II El Engr 322 focuses upon multi transistor circuits including differential amplifiers, feedback, stability, high current output stages and a variety of small and medium scale complementary MOSFET digital circuits. Our PCB based amplifier is an integral part of the second laboratory exercise of this second course. The block of instruction supported by EE 322 Lab 2 presumes a theoretical understanding of direct coupled differential and single bipolar junction transistor amplifiers. It also presumes an understanding of the origin of circuit poles and the methods for estimating and simulating their effects. The block of instruction which Lab 2 supports begins with a formal study of analog feedback. Feedback circuit topologies, feedback circuit implementation, criteria for stability, stability analysis and methods for stability augmentation are presented. We also choose to include output stage operation and limitations in this block of instruction. The theory of operation of push pull output stages includes signal swing limitations, methods for biasing, power dissipation considerations and frequency response. The Laboratory Exercise Within the pedagogical framework described above, we wished to create a laboratory exercise which would simultaneously illustrate both feedback and output stage concepts. The associated amplifier needed a differential input making it possible to reinforce the feedback concepts illustrated through operational amplifiers. The open loop gain of the amplifier needed to be low enough to be directly measured without saturation. P ge 1.32.2 Proceedings of the 2005 American Society for Engineering Education Annual Conference and Exposition Copyright (c) 2005, American Society for Engineering Education To illustrate the impact of pole compensation under feedback, the amplifier had to be designed inherently unstable at feedback factors near unity. Furthermore, the amplifier needed a common collector output stage through which output signal swing limitations under low resistance loads could be illustrated. The dc bias voltage of the output node needed to be adjustable across a range of about one volt above and below ground potential. The latter characteristic permits students some freedom of design in their output stage. In addition to the electronic characteristics, the amplifier had to support an exercise subject to additional practical limitations. The exercise had to complement out design, simulate, build and measure instructional cycle. This meant it our amplifier had to be simple enough to be simulated through our department standard circuit analysis software, OrCAD Cadence PSPICE. The exercise was further constrained to work within the limitation of our student laboratory equipment. Administrative constraints further limit the number of days which could be devoted to this exercise to seven 100 minute class meetings, spread over approximately three weeks, plus approximately six out of class clock hours. This is because the USAF Academy's curriculum is designed so that the average student can complete assigned work in 42 lesson meeting of a total of 150 minutes each. Finally, any hardware we developed had to be reasonably robust and be designed from readily available components. It also had to be fabricated in such a way that the inevitable student mis use could be corrected with reasonable ease. From the perspective of laboratory equipment, we have available an HP Model 54645A 100 MHz sampling oscilloscope, Kepco MPS620M 15V@1A DC power supplies and a Wavetek Datron 50MHz Model 80 function generator. Standard value leaded discrete components are available and may be interconnected through prototyping boards. One obvious alternative to the custom circuit approach we have taken in the subject exercise was the application of a commercial operational amplifier whose dominant pole frequency could be adjusted externally. The pole adjustment feature is essential to illustration of pole shifting and stability under feedback. Our experience has shown that such an approach has two distinct disadvantages. First, commercial operational amplifiers have very high gain bandwidth products. It would therefore very difficult to experimentally evaluate the loop gain of these amplifiers at low frequency. Second, commercial operational amplifiers offer students no opportunity to adjust internal parameters or to measure the condition of internal circuit nodes. The ability to verify circuit bias conditions and small signal gain across the amplifier is too important to ignore. Another approach we considered in the development of this exercise was simply to require students construct a common pre designed differential amplifier from discrete components. Our experience has shown this approach would inevitably involve student wiring errors which would slow the lab's execution and divert attention from the exercises objectives. Furthermore, the magnitude of parasitic capacitances inherent to proto boards and exact placement of components, would vary widely among student P ge 1.32.3 Proceedings of the 2005 American Society for Engineering Education Annual Conference and Exposition Copyright (c) 2005, American Society for Engineering Education designs. These variations would make it unlikely that every student would see the desired frequency dependent behavior or achieve success in pole compensation. The Amplifier Based upon the considerations described above, we concluded the best method for executing the proposed laboratory exercise was to build our own custom amplifier presented to students on a custom PCB. In order to keep the circuit simple and reasonably small, and to fu
author_names: Kenneth J Soda
title: A Custom Printed Circuit Board Differential Amplifier For Instruction In Undergraduate Analog Electronics

abstract: The Superconducting RF Test Facility (STF) at the High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC) Several digital low level radio frequency (LLRF) control systems were developed at the STF. The purposes of these developments are to construct a minimal configuration of the ILC LLRF system and achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Evaluations of digital LLRF control systems were conducted during the conditioning of eight superconducting cavities performed between October and November 2016. The digital LLRF control system configured for ILC was demonstrated and the performance fulfilled the required stability criteria of the accelerating field in the ILC. These evaluations are reported in this paper. INTRODUCTION A field programmable gate array (FPGA) based digital low level radio frequency (LLRF) control system will be employed in the International Linear Collider (ILC) to achieve the radio frequency (RF) stability requirements. The amplitude and phase stabilities of 0.07%(RMS) and 0.35 deg(RMS) respectively, are required for ILC [1] For the acceleration, the ILC utilizes 1.3GHz superconducting RF cavities, operating at an average gradient of 31.5MV/m. The RF system will be organized in approximately 400 RF stations. Each RF station is composed of one 10MW multi beam klystron driving 39 superconducting cavities. The feedback control is implemented to compensate the non repetitive disturbance and measurement noise. As only a single klystron is used to drive 39 cavities, the digital LLRF control system has to control the vector sum of the accelerating field of those cavities. The vector sum is the sum of the complex vectors representing the accelerating fields of all cavities. The size of one RF station in the ILC is approximately 60m in length, which may add a delay to the signal transmission from cavity to digital LLRF control system. One possible solution to reduce this problem is to distribute the LLRF control system into several sub systems, in a master slave configuration. The slave LLRF control systems calculate partial vector sums from the corresponding cavities and are placed near the cavities to shorten the signal transmission lines. The partial vector sums from all slave LLRF control systems are sent to the master LLRF control system via an sigitbw@post.kek.jp Figure 1: STF layout consists of normal conducting photocathode RF gun, two superconducting 9 cell cavities in the capture cryomodule driven by 800 kW klystron, eight superconducting 9 cell cavities (cavity number 1 8) in the CM 1 cryomodule, four superconducting 9 cell cavities in the CM2a cryomodules (cavity number 9 12) Both CM 1 and CM 2a cryomodules are driven by one 10MW multi beam klystron. optical communication link. One issue in this connection is the additional delay to the control loop caused by optical communication link, which may lead to system instability. This paper presents an evaluation of the digital LLRF control system with a master slave configuration and an investigation to confirm the effect of the optical communication link delay on the RF stabilities. The demonstration of the minimum setup of digital LLRF control system with the master slave configuration for the ILC was conducted at Superconducting RF Test Facility (STF) High Energy Accelerator Research Organization (KEK) during the cavity conditioning in the autumn of 2016. The layout of the STF is illustrated in Figure 1. A total of twelve cavities in two cryomodules, CM 1 and CM 2a, were installed as the STF 2 project [2] DIGITAL LLRF CONTROL SYSTEM WITH MASTER SLAVE The LLRF control systemwith master slave configuration will be adopted in ILC. Figure 2 shows the proposed system for one RF station. As a slave, the LLRF front end controller calculates a partial vector sum from the corresponding cavities and the result is sent to the central LLRF controller as a master, where the total vector sums are calculated and the klystron output are controlled. In order to accommodate large data transfer from the front end to the central system, an optical communication link is used. The minimum setup of the digital LLRF control system with master slave configuration for ILC was built at STFTHPAB116 Proceedings of IPAC2017, Copenhagen, Denmark ISBN 978 3 95450 182 3 3992 Co py rig ht (c) 20 17 CC B Y3. 0 an d by th er es pe ct iv ea ut ho rs 06 Beam Instrumentation, Controls, Feedback and Operational Aspects T27 Low Level RF Figure 2: Digital LLRF control system with master salve configuration for the ILC. As a slave, the LLRF front end controllers directly measure the signals from corresponding cavities and send the result to central LLRF controller as a master [1] KEK, which is illustrated in Figure 3. The 1300MHz signals from the cavities are down converted by mixing with 1310MHz local oscillator (LO) to get a 10MHz intermediate frequency (IF) After being digitized by the analog todigital converter (ADC) the IF signal is converted into an in phase component (I) and quadrature phase component (Q) [3] In the slave digital LLRF board, the partial vector sum of VS2 from corresponding cavities are calculated and sent to the master digital LLRF board through an optical communication link with an approximate length of 20m. In the master digital LLRF board, the total vector sum from partial vector sum of VS1 and VS2 is calculated. The delay introduced by the optical communication link can be compensated by introducing an additional delay in the partial vector sum of VS1 through the DLY module. To suppress the parasitic modes in the multi cell cavities, a fourth order conjugate poles digital infinite impulse response (IIR) filter [4] with a bandwidth of 250 kHz was implemented after the total vector sum calculation. The feedback and feedforward control algorithms are also performed in the master LLRF board. The digital signal is then converted into analog by a digital to analog converter (DAC) and is fed to the I/Q modulator to modulate the 1.3GHz RF signal from the master oscillator (MO) This signal is then used to drive the klystron, which drives the cavities. Both master and slave board are MTCA.4 standard hardware with 14 ch 16 bit AD9650 ADC (Analog Device, Inc. 2 ch 16 bit AD9783 DAC (Analog Device, Inc. and two FPGAs, Zynq 7000 and Spartan 6 (Xilinx Inc. These boards employ 162.5MHz for FPGA clock and 81.25MHz for ADC/DAC clock.
author_names: Sigit Basuki Wibowo

Na Liu

Toshihiro Matsumoto

Shinichiro Michizono

Takako Miura

Feng Qiu
title: Evaluation of Digital LLRF Control System Performance at STF in KEK
year: 2017

abstract: Abstract This paper presents a Low Cost Flexible Platform (LCFP) for measuring and characterizing photodetectors. This LCFP can characterize simultaneously up to 16 photodetectors and is composed by two main electronic circuit boards: a Transimpedance Amplifier Board (TIAB) and a Development Board (DevB) The TIAB was designed and optimized to reduce the noise increase, in order to convert photocurrents into voltages and at the same time, allowing the gain selection between one of the three values: 1 x 10 5 (low gain, LG) 1 x 10 6 (medium gain, MG) and 1 x 10 7 (high gain, HG) The DevB is composed by 16 analog inputs, 54 digital inputs/outputs and an internal Analog to Digital Converter (ADC) It is possible to digitally change the Upper End Voltage (UEV) of the ADC's range to voltages below +5 V. The DevB can convert into the digital domain each one of the 16 analog signals from the TIAB with a resolution of 48.9 nA, 4.9 nA and 0.5 nA for the highest value of UEV +5 V) and when either LG, MG or HG is selected, respectively. The measured data can be acquired in real time with LabView software, which allows the real time monitoring of the photocurrents for individual elements in the photodetector both through a numeric and graphical display. The light intensity can be defined by 8 digital outputs allowing 256 light intensity increments/steps from 0 to a maximum defined (by the lamp's manufacturer) light intensity. This LCFP can be used in industry to make quality control, e.g. when different test conditions are applied to the optical sensors/photodetectors and the user/customer need to quickly check if the response or performance is acceptable or resulted on any significant drifts. All these features combined with the low cost under 1400 EUR makes this LCFP a suitable tool to quickly evaluate the performance of optical sensors/photodetectors.
author_names: Jose Miguel Gomes

Jose Higino Gomes Correia

Joao Paulo Carmo
title: A Low Cost Flexible Platform (LCFP) for characterization of photodetectors
year: 2015

abstract: Purpose: To determine differences in overall tumor responses measured by volumetric assessment and bioluminescence imaging (BLI) following exposure to uniform and nonuniform radiation fields in an ectopic prostate tumour model. Materials and Methods: Bioluminescent human prostate tumor xenografts were established by subcutaneous implantation into male mice. Tumors were irradiated with uniform or non uniform field configurations using conventional in vivo irradiation procedures performed using a 225 kVp generator with custom lead shielding. Tumor responses were measured using Vernier calipers and by BLI using an in vivo imaging system. Survival was defined as the time to quadroupling of pre treatment tumor volume. Results: The correlation between BLI and tumor volume measurements was found to be different for un irradiated (R 0.61) uniformly irradiated (R 0.34) and partially irradiated (R 0.30) tumors. Uniformly irradiated tumors resulted in an average tumour growth delay of 60 days with median survival of 75 days, compared to partially irradiated tumors which showed an average growth delay of 24 days and median survival of 38 days. Conclusions: Correlation between BLI and tumor volume measurements is lower for partially irradiated tumors than those exposed to uniform dose distributions. The response of partially irradiated tumors suggests non uniformity in response beyond physical dose distribution within the target volume. Dosimetric uncertainty associated with conventional in vivo irradiation procedures prohibits their ability to accurately determine tumor response to non uniform radiation fields and stresses the need for image guided small animal radiation research platforms. INTRODUCTION Small animal models are a fundamental tool for robust preclinical radiobiological investigations. Technological advances in the clinic, such as intensity modulated and image guided radiotherapy, have significantly outpaced those for the irradiation of laboratory animals under experimental conditions which has commonly been performed using fixed kilovoltage sources with custom lead shielding for beam targeting and sparing of normal tissues (Hillman et al, 2001; Know et al, 1992) This translational gap between experimental radiobiology and radiation oncology has been narrowed with the implementation of small animal image guided radiation research platforms (Verhaegen et al, 2011; Zhou et al, 2010; Wong et al, 2008) which combine high resolution cone beam computed tomography (CBCT) with orthovoltage radiation sources for accurate beam targeting allowing treatment of a defined target through a process analogous to that of contemporary clinical practice. The implementation of these platforms in the laboratory represents a significant advancement for in vivo radiobiological investigations enabling preclinical evaluation of novel regimes including hypofractionation, dose painting and drug radiation combinations. Furthermore, the development of small animal radiation research platforms with on board optical imaging will offer significant potential in radiation biology. A range of optical imaging and spectroscopy methods are widely used for radiobiological studies to determine cellular responses at the molecular level (Palmer et al, 2012) Bioluminescence imaging (BLI) is a highly sensitive, non invasive in vivo imaging modality which measures photons generated by a luciferase reporter gene in the presence of the D luciferin substrate injected prior to imaging (Inouye et al, 2010) BLI has been used to assess tumour burden in a range of preclinical models for localised and metastatic disease (O'Neill et al, 2010; Tuli et al, 2012; Al Nakouzi et al, 2012) however, its application in monitoring the efficacy of radiation exposure responses has been limited (Lee et al, 2010) In the present study, we aimed to compare tumour volume and BLI measurements to determine differences in overall tumor response following exposure to uniform and nonuniform radiation fields in an ectopic prostate tumor model. This study also sought to provide in vivo support for the presence of out of field effects under non uniform dose distributions. MATERIALS AND METHODS Cell culture PC 3 luc2 Bioware Ultra (Caliper Life Sciences, Runcorn, United Kingdom) is a stably transfected luciferase expressing variant of the human prostate cancer cell line PC 3 (Kaighn et al, 1979) Cells were grown in RPMI (Roswell Park Memorial Institute) 1640 medium with 10% fetal bovine serum, 1% penicillin streptomycin (Gibco, Paisley, Scotland, UK) and maintained at 37degC in a humidified atmosphere of 95% air 5% CO2. Animals, tumor implantation and maintenance 6 8 week old male Fox Chase SCID (Severe combined immunodeficient) mice (Charles River Laboratories, Oxford, United Kingdom) were used as a xenograft model for PC 3luc2 cells. 1.5 x 106 cells in 100 ml of PBS (phosphate buffered saline) were implanted intra dermally on to the flank of animals under inhalant anaesthesia. 5 animal were assigned to each experimental group (control, uniform irradiated, partially irradiated) Animals received food and water ad libitum. All experimental procedures were carried out in accordance with United Kingdom Home office approved protocols for in vivo experimentation. Irradiation procedure Tumors were grown for 4 8 weeks until reaching a pre treatment volume of around 100 mm3. Animals were assigned to three treatment groups, un irradiated controls, 8 Gy irradiated animals delivered as a uniform field and 8 Gy irradiated animals delivered as non uniform field in which 40 60% of the tumor volume was irradiated. Animals were restrained and custom lead shielding used to expose the complete or partial tumour volume to 225 kVp X rays using a X Rad 225 generator (Precision X ray Inc, North Branford, Connecticut, USA) A dose profile was generated using Gafchromic RTQA2 film (Ashland, Covington, Kentucky, USA) placed under the lead shielding which show scattered dose fell to less than 10% of the target dose within 1 cm off axis as shown in figure 1. Animals were irradiated at a dose rate of 0.52 Gy min 1. Tumour volume measurements and BLI Tumor volume was determined three times a week from Vernier caliper measurements in three orthogonal dimensions. Tumour bearing mice were imaged weekly using an IVIS 100 (Caliper Life Sciences) Animals were intraperitoneally injected with Dluciferin potassium salt (Caliper Life Sciences) at a concentration of 150 mg/kg and imaged 15 minutes after injection as determined from BLI kinetic studies in the same tumor model. The distribution of detected photons was overlaid onto a grayscale photographic image and a region of interest (ROI) manually selected. Signal intensity was quantified in photons/second/squared centimetre/steradian (p/s/cm2/Sr) for a ROI selected manually by applying the same threshold to each of the images using Living Image Software (Caliper Life Sciences) Statistical Analysis The correlation between tumour volume and BLI measurements was assessed using a linear regression of the form yy mmmm cc, where x is the measured volume, y the BLI value, m the slope and c the y intercept of the linear fit of the data. Significant correlation was evaluated using a two tailed t test on m, with a significance threshold of 0.05. All calculations were carried out using (GraphPad Prism, Version 5.01) RESULTS Correlation of tumor volume and BLI measurements Correlation of tumor volume and BLI measurements was determined for control, uniformly irradiated and partially irradiated tumours in a heterotopic prostate xenograft model. Photon emission from a manually selected region of interest showed maximum flux at 15 20 minutes after intraperitoneal injection of D luciferin in animals pretreatment. Control and irradiated animals showed no significant difference in the kinetics of bioluminescence signal at the beginning of the experiment or when maximum tolerated tumour volume was reached at the end of the experiment (data not shown) Comparison of BLI and tumour volume for control, uniformly irradiated and partially irradiated tumours is shown in figure 2. Linear regression analysis showed significant correlation between tumor volume and BLI for control tumors (R 0.6123) A less strong correlation between tumor volume and BLI was observed for uniformly irradiated tumours (R 0.3417) and the least significant correlation shown for partially irradiated tumors (40 60% tumour volume; R 0.3063) Significance testing of these correlation coefficients using a t test indicated statistically significant correlation for control (p 0.01) and uniformly irradiated animals (p 0.02) but no significant relationship for partially exposed tumors (p 0.08) Tumor growth delay and overall survival Tumor volume measurements are shown for control, uniformly irradiated and partially irradiated animals in figure 3a. Comparing the data for control with uniformly irradiated tumours showed a significant growth delay of around 60 days which is reflected in the median survival of 14 and 75 days respectively as shown in figure 3b. Comparison of control with partially uniformly irradiated tumours showed a significant growth delay of around 24 days which is reflected in the median survival of 14 and 38 days respectively as shown in figure 3b. The mean fractional uncertainty in tumor volume measurements was found to be 0.12 for control animals compared to 0.26 for partially irradiated and 0.24 for uniformly irradiated animals. DISCUSSION This study aimed to determine differences in the overall tumor response measured by volumetric assessment and BLI in un irradiated and irradiated tumors exposed to uniform or non uniform radiation fields. These experiments were conducted in the context of assessing BLI as a means to determine the effective spatial dependency of radiobiological effects occurring outside of the primary treatment field and to assess if this could be achieved
author_names: K T Butterwortha

K M Redmonda

S J McMahona

A J Coleb

H O McCarthyc

M O'Sullivanb

A R Hounselld

K M Prisea
title: Conventional in vivo irradiation procedures are insufficient to accurately determine tumor responses to non uniform radiation fields
year: 2016

abstract: A prototype wireless guided wave inspection system is developed to inspect layered structures such as aircraft wing. The system includes a stationary antenna and an active antenna as transceivers, an on board antenna as transponder, and PVDF comb transducers for generating and receiving ultrasonic Lamb waves. Preliminary experiments on a 0.8mm aluminium plate with a 12mm long, 50% through wall depth crack clearly demonstrated its feasibility of defect detection. Potential applications on an E2 plane wing section are also presented. This system showed great potential of remote, leave in place and in service defect detection and condition monitoring. Introduction: The flight environment of an aircraft is usually very harsh due to large changes in humidity, temperature, pressure, speed, and loading conditions. These effects cause a lot of stress to aircraft frame. As a result, corrosion, delamination, cracks, disbonds, and other failures creep in once the aircraft is in service for some time. Fault diagnosis and prognosis is very important in health monitoring or condition based maintenance of the aircraft structures. If one can measure the degradation of a component before it actually fails, it will provide ample time for maintenance engineers to schedule a repair, and to purchase or fabricate replacement components before the components actually fail. The end result will be lower cost and higher availability. Ultrasonic guided waves have been used in non destructive inspection (NDI) of various defects in aircraft structures, with major advantages like fast scanning capabilities, low cost, and long range inspection. Small and reliable guided wave sensors can also be leave in place on the structures for online monitoring, which is more convenient for real time damage evaluation. All current data acquisition techniques, however, still rely on cable connections from a waveform generator to the inspection sensors, and then to a waveform displayer or oscilloscope for analysis. In this paper, we proposed a novel wireless system for structural integrity monitoring of an aircraft. The prototype system includes a passive antenna as a transmitter, an on board antenna as transponder, a PVDF comb transducer for generating and receiving ultrasonic Lamb waves in a layered structure, and a portable active antenna as a receiver. A series of experiments on a 0.8mm thick aluminium plate with a 12mm long, 50% through the wall crack clearly showed its feasibility in defect detection. Conventional wired approach and semi wireless approach are also presented for comparison. Some practical leave on board antennae for aircraft wings are also discussed, along with preliminary experiments. Approaches: One of the objectives of this study is that NDI sensors should be low cost, compact, passive, conformable to the aircraft structure, and can be interrogated in a wireless manner. The wireless capability allows the aircraft to be monitored all the time. Boeing has performed an internal study, which concludes that 85% of maintenance effort is spent on tearing down and re assembling the components. Only 15% of labour is spent on actual inspection. Hence the maintenance cost can be saved significantly by a wireless leave in place approach. For this objective to be materialized, we proposed a technical approach as shown in Figure 1. That is, a PVDF guided wave sensor is attached to the test structure, with its input/output connected to an on board antenna to feed in interrogate electrical signal and send out its response. The interrogate signal can be transmitted by a transmission antenna through a cable connected to the signal generator, and the return signal captured by a receiving antenna cable connected to a signal receiver. In this case, both the transmission and receiving antennae can be moved around and collect information about the health status of the structure. The conventional wired approach does not use antennae as information transponder; usually co axial cables are utilized to connect the signal generator, the sensor and the signal receiver together and it is the state of practice in industry. The choice of PVDF sensor is obvious since it is low cost, compact, passive, conformable to the test structure, and easy installation. We will discuss more about its design and utilization in the next subsection. Ultrasonic guided wave Crack Signal generator Signal reciever PVDF comb transducer Radiated and returned signal FIGURE 1 The schematic view of wireless inspection system for crack detection. 45.8cm PVDF Comb Transducer Crack Excited Lamp Wave 15.3cm
author_names: X Zhao

Chiman Kwan

Kwai Man Luk
title: WIRELESS NONDESTRUCTIVE INSPECTION OF AIRCRAFT WING WITH ULTRASONIC GUIDED WAVES
year: 2004

abstract: This paper presents non contact ultrasonic imaging techniques with air coupling. The work is conducted as a part of the German research project MaTech. Project partners are Airbus, Bremen, IntelligeNDT, Erlangen, Ingenieurburo Dr. Hillger, Braunschweig, the Technical University of Hamburg Harburg and DLR, Braunschweig, as a subcontractor. A modular and open ultrasonic imaging system (demonstrator III) which provides the capability for basic research of air coupled ultrasonic techniques for composites has been developed. Highlights are: a freely programmable transmitter, fast full wave data recordings (12 bit) and software Cand D scans. Especially promising testing results can be achieved by the application of suitable transmitter signals and processing of the received signal. In this paper, both frequency modulated and coded signals are considered for transducer excitation. This works particularly well for broadband air coupled transducers, for which the signal is chosen adaptively. For the received signal, a matched filter processing is applied depending on the transmitter signal. Measurement results show a significant improvement of the signal to noise ratio especially for thicker components. Introduction: The increase of composite materials for aircraft applications requires a growing need for NDT. The aircraft industry is using more and more thick CFRPand CFRP sandwich components with honeycomb and foam core. Those materials are highly attenuative. Sandwich materials can only be penetrated with frequencies in a range of about 50 to 500 kHz. The airborne ultrasonic technique avoids the disadvantages of the common ultrasonic technique with coupling liquid or coupling paste like time consuming cleaning, incoming water, air bubbles in immersion technique, etc. [14] On the other hand, the acoustic impedance mismatch between solids and gas (air) produces an amplitude loss of more than 150 dB using a standard ultrasonic equipment. Therefore special transducers with an impedance matching to air, a powerful excitation of the sender and a matched ultra low preamplifier are required. Results: Ultrasonic system. The developed air coupled ultrasonic imaging system USPC 4000 AirTech (Fig. 1) is a further development of the "demonstrator 3" [5] of the MaTech project. This system provides high pulse repetition frequencies in order to get high scanning speeds. The hardware built in an industrial PC with Windows operating system consists of programmable high power pulser with a digital arbitrary generator, an ultra low noise preamplifier, a main amplifier and a ADC board with a resolution of 12 bits. All measuring functions such as amplitude (gated peakdetector) and time of flight measurements are carried out by software. The system does not only provide C scanning but also full wave scans with software A B C Dscans. Additional functions are echotechnique (in order to measure the distances between the transducers and the specimen) and the application of chirp and coded signals. The software also enables digital filters for the enhancement oft results. The system is working with transducers from different manufactures. Fig.1: Block diagram of USPC 4000 AirTech Transducers Several transducers from different manufactures have been evaluated for ultrasonic imaging. The most interesting parameters are sensitivity, centre frequency, bandwidth, focus point and beam diameter. Most of them are resonant transducers with a small bandwidth in order to get a high efficiency. A few of them showed side lobes in their sound fields. For optimising the distances between transducers and specimen, it is useful to record the sound field with a ball reflector. In order to get a high power broadband pulse, a stack transducer [6] (Fig. 2) has been investigated. This kind of transducer consists of eight elements, which are acoustically coupled and electrically insulated. At the back wall of the piezo element 1, an acoustic damping is situated, at the front (sound output, element 8) an impedance matching to air is situated. All elements are excited with delayed pulses S1 to S8. The delay times t2 to t8 are adjusted in the way that the passing pulse from element 1 through element 2 to 8 is amplified by the pulses S2 to S8. In the ideal case, the output of the element 8 provides an 8 fold higher pulse compared with a standard transducer. This technique can also be applied on the receiver side. The receiver stack transducer built in the same way, delivers 8 delayed pulses which have to be added with the right phases. Theoretically, a gain of 18 dB can be reached in comparison with a single element transducer on the receiver and on the transmitter side. For this kind of stack transducer, an ultrasonic system with eight channels has been developed. But the results show some disadvantages: The acoustic coupling between eight elements cause a ,ringing" so that no single highly damped pulse has been generated. Therefore, the echo technique could not be used. Also the impedance matching to air was not very successful, so that the sensitivity s, defined by:
author_names: Wolfgang Hillger

Malte Ahrholdt

Herrmann Rohling

Rudolf Henrich
title: Non Contact Ultrasonic Imaging Techniques for Composite Components
year: 2004

abstract: Noncardiac chest pain is characterized by recurrent and often incapacitating chest pain without demonstrable cardiac abnormality. As many as 30% of patients with suspected angina may have this condition [1] In the United States, the annual incidence is estimated to be 180 000 cases [2, 3] Although some patients are reassured by the absence of a definable abnormality, many continue to have pain that prompts frequent visits to physicians and emergency departments and even results in hospitalization [4, 5] In many cases, the esophagus has been determined to be the source of such pain. Esophageal manometry can identify motor dysfunction in as many as 25% of patients with noncardiac chest pain [6, 7] and additional provocative tests show motor and other abnormalities in another 15% to 25% [6 10] Most such patients have gastroesophageal reflux disease [3] Some studies of the sensations evoked by balloon distention in the esophagus have suggested that 48% to 60% of such patients have altered sensory perception [11 13] but other studies have not confirmed this finding [9, 10, 14] Most studies of esophageal motor function have examined the contractile properties of the esophagus, but little attention has been paid to the biomechanical and sensory properties, primarily because of technical limitations [15 17] A new technique, impedance planimetry, allows investigation of sensory and biomechanical properties in the intact human gut [15, 16, 18, 19] This technique provides a way to assess the cross sectional area of the lumen in a selected plane at a range of distending pressures. It also permits quantification of the resistance offered by the biomechanical and contractile properties of the wall and of the sensory responses that are provoked by balloon distention. We used impedance planimetry to determine whether a sub group of patients with unexplained chest pain has abnormal biomechanical esophageal muscle properties and abnormal esophageal sensory nerve function. Methods Participants We studied 24 consecutive patients with unexplained noncardiac chest pain who were seen on an outpatient basis: 10 men and 14 women (mean age, 48 years [range, 30 to 74 years] All patients were referred by cardiologists after extensive cardiac evaluations showed no cause for the chest pain and, in many instances, after various empiric therapies proved ineffective. Patients had no comorbid illnesses and had either normal coronary arteries or insignificant coronary artery disease as shown by results of angiography, stress thallium testing, or stress technetium 99m methoxy isobutyl isonitrile (MIBI) In addition, all patients had extensive gastrointestinal evaluations. The results of these evaluations included normal findings on upper gastrointestinal endoscopy with esophageal biopsy, normal esophageal manometric results, and either normal results of 24 hour pH study or no response to 6 weeks of omeprazole, 20 mg per day. Patients were included only if they had at least one episode of chest pain per week and if their symptoms had persisted for more than 3 months. We also studied 12 healthy controls, 5 men and 7 women (mean age, 35 years [range, 24 to 63 years] who were recruited by a hospital advertisement. The controls were asymptomatic, were not taking any medication, had not had any previous thoracic or gastrointestinal surgery, and had normal physical examinations. All participants gave written informed consent, and the Human Investigation Review Board of the University of Iowa College of Medicine approved the study. Impedance Probe and Measuring System The equipment, which consisted of a probe and a signal processing system, has been described in detail elsewhere [15, 16, 19] The flexible plastic probe, 6 mm in diameter, contained four ring electrodes (two outer and two inner electrodes) and five side holes. A thin latex balloon, 4.5 cm long, was tied around the probe to enclose the four ring electrodes and three of the side holes (Figure 1) Two of these were infusion side holes that were used to distend the balloon, and the third was a perfusion side hole that was used to measure intraballoon pressure. The remaining side holes, one located 2.5 cm proximal to the balloon and the other located 2.5 cm distal to the balloon, were used to measure intraesophageal pressures. The side holes were perfused with 0.018% NaCl solution at a rate of 0.2 mL/min, and the intraluminal pressures were measured using a low compliance pneumohydraulic perfused system (Arndorfer, Milwaukee, Wisconsin) connected to external transducers (Gould, Inc. Essex, United Kingdom) The leveling container, a 400 mL plastic jar half filled with 0.018% NaCl, was connected to the probe with a plastic tube. The signal processing system (Figure 1) consisted of a generator that gave a constant alternating current of 100 A at 5 KHz, an amplifier, an impedance detector, an analog digital converter, and a computer [15, 16, 19] Figure 1. Schematic representation of the probe and the signal processing system used for impedance planimetry of the esophagus. Study Protocol All participants were studied after an overnight fast. Oropharyngeal anesthesia was achieved with a local spray of dyclonine hydrochloride (Dyclone, Astra, Westboro, Massachusetts) The lubricated probe was passed through the mouth until its tip was located 55 cm from the teeth. Participants were asked to lie on a bed, which was tilted at the head end by 30 degrees. After a rest period of 10 minutes, the catheter was gradually withdrawn until the balloon lay across the lower esophageal sphincter. The lower esophageal sphincter was identified as a zone of high resting pressure that decreases with swallows. The catheter was removed and taped in position so that the balloon lay 10 cm above the lower esophageal sphincter, where all measurements were obtained. After a second rest period of 10 minutes, the balloon pressure was set at 0 according to the resting intraesophageal pressure by adjusting the height of the leveling container, which was adjacent to the participant but behind a screen. Thus, participants were blinded to the degree of inflation. Next, the balloon pressure was increased in steps of 5 cm H2O to 50 cm H2O or greater by raising the leveling container and infusing 0.018% NaCl (at 37 C) into the balloon. After each distention, the balloon was deflated by lowering the leveling container and was reinflated after a rest period of 3 minutes. Each inflation was maintained for 3 to 5 minutes or until the cross sectional area reached a new stable baseline between reactive contractions. At this steady state, the cross sectional area was measured and the sensory responses were noted. Participants were given a symptom chart and were asked to grade their sensation as follows: grade 0, no sensation; grade 1, a sensation of fullness or distention; grade 2, moderate (tolerable) discomfort; and grade 3, severe pain. Because no controls had discomfort or pain at inflation pressures as great as 50 cm H2O, serial inflations of the balloon were continued until the controls reported pain or until a pressure of 65 cm H2O was reached. In the patient group, the inflations were continued until typical chest pain was evoked or until a pressure of 50 cm H2O was reached. During inflations, participants were asked to refrain from swallowing and to signal the onset of reflex swallows. Reflex swallows were noted to distinguish primary (that is, aborad) propagating contractions, which are initiated by swallowing, from secondary peristalsis, which consists of aborad propagating contractions induced by local distention of the esophagus. Measurements and Data Analysis The balloon cross sectional area was measured according to the field gradient principle [20 22] When a current, I, is induced by the two outer ring electrodes in a cylinder of conducting medium, the potential difference, V, between the two inner (detection) electrodes is V equals I R (Ohm's law) where R is the impedance of the conducting substance. R can also be expressed as d c1 the cross sectional area1, where d is the distance between the detection electrodes and c is the conductivity of the fluid. If I, d, and c are constants, V is inversely proportional to the cross sectional area. The computer software provided output that was directly proportional to the cross sectional area. The data for the cross sectional area and intraluminal pressure were stored on diskettes. The records, visualized off line on a computer, were analyzed with a software program by an author who was blinded to the participants' clinical details and results of sensory function. The following are definitions of and formulas used to calculate the variables. Sensory Responses The balloon pressure that induced first sensations of fullness, moderate discomfort, and pain were noted for each participant, and the mean values for the threshold pressures that induced each sensation were calculated. Passive Biomechanical Properties Cross sectional area: At each level of balloon inflation, the radius was calculated from the new steady state baseline cross sectional area. Because previous studies [18, 19, 23] had shown that the measurements of the cross sectional area conform to the linear portion of the calibration curve at pressures as great as 40 cm H2O, and because 35% of patients could not tolerate balloon distention beyond this level, the cutoff pressure for calculations of biomechanical variables was 40 cm H2O. Circumferential wall tension (T) The total force applied to stretch a segment of the wall was calculated [15, 16] as T r dP, where r is the balloon radius (r square root of the cross sectional area P 1) and dP is the transmural pressure difference (Law of Laplace) Transmural pressure was defined as the difference between the balloon pressure and the resting pressure in the esophagus, with the assumption that esophageal intraluminal pressure at rest is the same as intrathor
author_names: S S C Rao

Hans Gregersen

Bernard Hayek

Robert W Summers

James Christensen
title: Unexplained Chest Pain: The Hypersensitive, Hyperreactive, and Poorly Compliant Esophagus
venue: Annals of Internal Medicine
year: 1996

abstract: ILC work at Illinois has concentrated primarily on technical issues relating to the design of the accelerator. Because many of the problems to be resolved require a working knowledge of classical mechanics and electrodynamics, most of our research projects lend themselves well to the participation of undergraduate research assistants. The undergraduates in the group are scientists, not technicians, and find solutions to problems that, for example, have stumped PhD level staff elsewhere. The ILC Reference Design Report calls for 6.7 km circumference damping rings (which prepare the beams for focusing) using "conventional" stripline kickers driven by fast HV pulsers. Our primary goal was to determine the suitability of the 16 MeV electron beam in the AO region at Fermilab for precision kicker studies.We found that the low beam energy and lack of redundancy in the beam position monitor system complicated the analysis of our data. In spite of these issues we concluded that the precision we could obtain was adequate to measure the performance and stability of a production module of an ILC kicker, namely 0.5% We concluded that the kicker was stable to an accuracy of ~2.0% and that we could measure this precision to an accuracy of ~0.5% Asmore a result, a low energy beam like that at AO could be used as a rapid turnaround facility for testing ILC production kicker modules. The ILC timing precision for arrival of bunches at the collision point is required to be 0.1 picosecond or better. We studied the bunch to bunch timing accuracy of a "phase detector" installed in AO in order to determine its suitability as an ILC bunch timing device. A phase detector is an RF structure excited by the passage of a bunch. Its signal is fed through a 1240 MHz high Q resonant circuit and then down mixed with the AO 1300 MHz accelerator RF. We used a kind of autocorrelation technique to compare the phase detector signal with a reference signal obtained from the phase detector's response to an event at the beginning of the run. We determined that the device installed in our beam, which was instrumented with an 8 bit 500 MHz ADC, could measure the beam timing to an accuracy of 0.4 picoseconds. Simulations of the device showed that an increase in ADC clock rate to 2 GHz would improve measurement precision by the required factor of four. As a result, we felt that a device of this sort, assuming matters concerning dynamic range and long term stability can be addressed successfully, would work at the ILC. Cost effective operation of the ILC will demand highly reliable, fault tolerant and adaptive solutions for both hardware and software. The large numbers of subsystems and large multipliers associated with the modules in those subsystems will cause even a strong level of unit reliability to become an unacceptable level of system availability. An evaluation effort is underway to evaluate standards associated with high availability, and to guide ILC development with standard practices and well supported commercial solutions. One area of evaluation involves the Advanced Telecom Computing Architecture (ATCA) hardware and software. We worked with an ATCA crate, processor monitors, and a small amount of ATCA circuit boards in order to develop a backplane "spy" board that would let us watch the ATCA backplane communications and pursue development of an inexpensive processor monitor that could be used as a physics driven component of the crate level controls system. We made good progress, and felt that we had determined a productive direction to extend this work. We felt that we had learned enough to begin designing a workable processor monitor chip if there were to be sufficient interest in ATCA shown by the ILC community. Fault recognition is a challenging issue in the crafting a high reliability controls system. With tens of thousands of independent processors running hundreds of thousands of critical processes, how can the system identify that a problem has arisen and determine the appropriate steps to take to correct, or compensate, for the failure? One possible solution might come through the use of the OpenClovis supervisory system, which runs on Linux processors and allows a select set of processors to monitor the behavior of individual processes and processors in a large, distributed controls network. We found that OpenClovis exhibited an irritating amount of sensitivity to the exact version of the Linux kernel running on the processors, and that it was poorly equipped to help us sort through problems that arose through conflicts so deep in the operating systems of the processors. But once this issue was addressed, we found that it performed as expected, recognizing crashes and process (and processor) failures. less
author_names: George D Gollin

M Davidsaver

Michael Haney

Michael Kasten

Jason Chang

Perry A Chodash

Will Dluger

Alex Lang

Yehan Liu
title: International Linear Collider Accelerator Physics R&D
year: 2008

abstract: The experience of large calorimeters, in passed and actual experiments shows that the calibration is an extremely long and methodic task, implying several redundant methods in hardware and software as well. If, as expected nowadays, the Higgs has a mass under 150 GeV, its discovery in gg decay by LHC experiments will rely heavily on the resolution of the ECAL. The precise measurement of these two gammas will depend in particular upon an accurate calibration (the constant term is expected 0.5% in CMS) and upon a precise g/e energy scale. The knowledge and the mastering of the calibration will play a major role. We describe here the electronic system, that has been developed at LAPP to update permanently the calibration of the electronic readout chain of CMS ECAL, during data taking. 1 The CMS ECAL and its read out The target characteristics of CMS ECAL make this project very challenging in terms of resolution, hadron rejection, particles isolation etc..Its characteristics are described in several publications [1,2,3] and I will only remember the principles of its read out As this crystal calorimeter is fully immerged in the magnetic field of 4 Teslas, the choice was made to read out the crystals by APD photodetectors. A very aggressive R&D has been sent since 4 years and is being concluded by the production of 120 000 of these detectors. The first pre production is actually under tests. Each crystal will be equipped with 2 Hamamatsu APD's, in parallel, and the read out is made by sets of 2 read out cards, grouping 5 channels each. On the read out card are implemented A/ 5 chips "FPPA" developed in Harris UHF1X process, which are multi gain shaping amplifiers (gains 1, 4, 8, 32) with a specific logic to indicate the first amplifier that does not saturates for the sampling (40 MHz) being made. The chosen amplifier is marked by 2 bits, added B/ 5 commercial flash ADC 12 bits (Analog Device AD 9042, previously developed for USAF, in Bipolar XFCB Process) that digitize the amplitude every 25 ns. C/ 5 serializers that convert the parallel 20 bits words (40 MHz) to a serial stream out (0.8GB.s) for the opto coupler. D/ One opto coupler, developed in CHFET ASGA process, that transmits the digital information through a set of 3 fibers to the Read Out System ECAL (ROSE) card that, in the control room, links the front electronic to the general DAQ and to the trigger. E/ One "Control Chip" (CTRL) developed in DMILL BICMOS process, that receives, from the ROSE card, through optical fibers, the adjustment parameters for the readout. It deserializes and dispatch them to individual chips. Apart from the DAC, all the chips are full custom and have been developed at CERN by Princeton group. The final version of the whole system has been put in test beam for the first time in August and the analysis is under way. 2The calibrations of ECAL The task can be divided into 3 general topics [4] 1. Before being mounted on the detector, all the supermodules will be pre calibrated on a dedicated electron test beam to provide an initial precise set of calibration coefficients for each channel. 2 During data taking, the day to day, channel to channel calibration inside a same region will be updated during sterile cycles of the machine by light injection and charge injection. This calibration is made by alignment of the response of individual channels belonging to a same region. A region can be defined as a group of channels sharing the same bunch of fibers. 3 The medium and long range (in time) absolute calibration of the whole detector will rely on W and Z decay measurements. The calibration of ECAL is then organized on several partially redundant methods: 1. Injections at the inner edge of the crystals of light pulses produced by two lasers and passing through a fiber distribution system: This system will follow the response of the ensemble crystal readout chain to light pulses along the time. The first pulse, at the middle of the scintillation spectrum (420 nm) will follow the shifts of the overall system (in particular due to loss of transparency of crystals under irradiation)[5,6] The second one, at 600nm is almost insensitive to transparency losses and will follow the APD gain and electronic shifts. 2 An independent system of charge injection at the input of the read out chain will follow the shifts of the readout chain and cross calibrate the different gains of the preamplifiers. 3. "In situ" calibration with physics events at low energy, the isolated electrons will be measured precisely by the tracker and their momentum compared with the response of the calorimeter. At medium energy (around 20 GeV) the W's and Z's will provide an absolute calibration for the whole detector. According to luminosity, this "in situ" calibration will need between a few days and a month during which the local calibrations will have to be adjusted. 3 The calibration by Charge injection The project consist of adding on the readout card a) one Test Pulse Logical System (TPLS) implemented inside the CTRL, b) one DAC, c) 5 injectors, producing on request a current pulse at the input of each FPPA. These pulses have a shape identical to the APD's one and their common amplitude is proportional to the order given to the DAC. The system has been developed at LAPP (Annecy) in DMILL process, with following requirements 1. no perturbation of the characteristics of the chain (in particular no add of correlated noise, no cross talk, nor any deterioration of characteristics) 2. at least as precise and reliable as the readout chain 3 robustness to eventual shifts due to irradiation damages 4. Use of existing supplies (0/5V) and very low power consumption 3.1 The Injector The injector is the most critical part of this system. It has to cover the total dynamic of the APD's (pick current of 4mA, and a full scale charge of 48 pC) with a linearity better than 0.5 It has to be radhard up to 10 n/cm and 3 Mrads in g (10 years of LHC irradiation) The shape is a fast negative fall followed by an exponential rise (t=15ns) with a technical dispersion in amplitude and time lower than 10% The PSRR (Power Supply Rejection Ratio) against the supply and the DAC line has to be as low as possible. Since 1998, we have made 5 generations of prototypes a first one in AMS to test the principle, then two in CMOS, one in CMOS Bipolar and a last version integrating the 5 channels in one chip. In the final design, the injector is made of 3 components 1. The trigger part, that adapt the PECL window signal (400ns width) received from the CTRL to levels compatible with the pulse generator stage. The edge of signals are also slightly reshaped to avoid the time jitter in the trigger of calibration pulses. 2 The amplifier that translates the voltage level produced by the DAC into a current level, transmitted to the pulse generator stage 3. The pulse generator is mainly a two branch bipolar circuit. The trigger splits the flowing current from one branch to the other one and the capacity Cout (60pF) previously charged is rapidly discharged and then recharged through Rout (250 O) and the preamplifier (Zi ~7 O) The decay time of the pulse is completely fixed by Rout Cout For precision and flexibility, the Cout has been placed outside the chip. Figure 1 Principle of the Injector 3.2 The DAC In a previous version, we have tested a commercial circuit, Analog Device AD 8582A in CB CMOS technology. This DAC is a parallel input, 12 bits, 0/4Volts, 5mA output, supplied on 0/5Volts, its dissipation is 5mW at rest. Its reference voltage level can be measured on an output pad. This chip has been extensively tested in lab and in irradiation beams. It fulfills the calibration requirements In a second step, a 10 bits DMILL version has been founded in view of assembling the whole project in one chip. This DMILL DAC is still under investigations due to process difficulties during foundry. 3.3 The control chip The control chip first amplifies the amplitude of the 40MHz clock and of the data's received from the optocoupler; then it recognizes, interprets and dispatches the orders to the different parts of the readout card. 4 The R&D 4.1 The tools Figure 2 shows the chain that has been mounted at LAPP to measure the linearity, the dispersion and the stability of different components of the project. This chain is based on a PC linked to a VME and CAMAC crates for charge measurements. It is also linked to a Keithley Multimeter 2020 by GPIB link for levels measurements. An overall monitor Labview(r) program makes systematic rampings on the DAC with charge and levels measurements at each step. The linearity of the injector has been measured in tension (at the edges of Rout) which is the most precise and in total integrated charge, after Cout In some runs, we have also verified by on a LECROY 9361 linked by GPIB that the shape was not affected. Figure 2 Principle of the Measurement chain For irradiation tests, we moved an identical chain on the different available sites. Figures 3 set up used for irradiation tests After a preliminary test on the Nuclear plan Ulysses at Saclay (IR1) we have used the SARA installation at Grenoble (France) (IR 2) and after it's shut down, the CERI installations at Orleans (IR 3,4 and 5) where the irradiation facility had been moved. These beams [7,8] produce neutrons by stripping of deutons on a thick beryllium target. The average energy of these neutrons is 6 MeV and the FWHM is 6 MeV. Theses beam have a photon contamination that has been evaluated to 3.6 kGy for an integrated dose of 2*10 n/cm The fluence depends on the distance to the target and can be adjusted up to 10 n/cm/ hour. We have also used the 72 MeV proton beam of PSI (Villigen, Switzerland) (IR 6 and 7) The correction parameter for protons is 2 and the equivalent integrated dose for this irradiation was 4 10 n/cm2. We have also used a photon Cobalt source facility at PSI to
author_names: Yong Wook Baek

Jean Pierre Peigneux

Pierre Yves David

J P Mendiburu

Joseph M Ditta

D I Boget
title: Calibration chain developed at LAPP for the ECAL of CMS
year: 2000