Normal timing discriminators like the constant fraction discriminator cfd ortec 935 are designed for negative signals. The roentdek cfd constant fraction discriminator units can be used for improving. Eee nuclear science symposium san francisco, ca october 2128, 1995 the submitted manuscript has been. Request pdf reliability prediction of constant fraction discriminator using modified pof approach in this paper, the introduction, functioning and importance of constant fraction discriminator. In general, if this width is not ideal, the laser sync signal can be passed to a discriminator circuit that can control its output pulse width. Constant fraction discriminator cfd is a perfectly suitable solution for the lowjitter digitization of analogue signals in systems that use microchannelplates or channeltrons as electron multiplier devices.
Constantfraction discriminator how is constantfraction. A fullintegrated pulseshape discriminator for liquid scintillator counters1 o. Pdf format for this model number or go to our download area where all the data sheets are available and are listed by. Pdf the constant fraction discriminator in pulsed time. Your shares transfer just fine, and continue to exist. A receiver channel technique that tries to combine the advantages of the. Figure 5 shows the qdc firmware block diagram and pulse parameters. We have several different kinds of constant fraction discriminators in the lab. The paper presents a new construction of an optical pulse amplitude monitoring unit pamu used in a transceiver of free space optics.
Constant fraction discriminator in pulsed timeofflight. What is it mean to say that some quantity is a constant fraction of another quantity. The constant fraction discriminator the main component of this digital trigger is the pulse shape analysis, done on channel level, which consists of a digital implementation of a constant fraction discriminator cfd. Investigation of various shaping methods for the development of a. Cf constant fraction discriminator sr constant fraction discriminator with slow risetime reject uld on differential constant fraction discriminator window mode sca uld off integral constant fraction discriminator only lld in operation dt n normal deadtime operation, deadtime given by the width of the positive output signals. Thanks to the sampled signals, smart algorithms making best use of the pulse shape can be used to improve time resolution. In order to understand the inefficiency of the calorimeter trigger in the hypercp experiment, we have studied the behavior of the constant fraction discriminator cfd when two pulses that are close together in time are sent through it.
Design and performance results for three different fullyintegrated gated baseline restorer blr circuits used in a new pet currentmode frontend cmos as. Constant fraction discriminators cfds use a constant fraction or percentage of the input pulse to precisely determine the timing of the output pulse leading edge relative to the input signal. Measurements of timing resolution of ultrafast silicon. The computer, a general automation spc 1685, also supplies pointing commands which are used to drive the beam scanner. Failure of the constant fraction discriminator by kristin luery july 9, 2003 in order to understand the inefficiency of the calorimeter trigger in the hypercp experiment, we have studied the behavior of the constant fraction discriminator cfd when two pulses that are close together in time are sent through it. I p a monolithic, constantfraction discriminator using distributed rc delayline shaping m. The model 2128 has a dccoupled 50 ohm input which accepts negative pulses. In particular, the integration gate for the fast component has to be positioned without jitter for pulseshape analysis. Nuclear instruments and methods in physics research a 410 1998 220228 a fullintegrated pulseshape discriminator for. Some signals do not have a sharp maximum, but short rise times. Investigation of the time performance of a lyso array for.
A monitor is also provided to observe the constant fraction shaped pulse to verify that the delay is correct. A constant fraction discriminator cfdworks by looking at the whole signal and emits the logic pulse when the input signal reaches a certain fraction of the peak value. At some point the sides of the timing peak merge into the random coincidence background. The suitability of several onchip constant fraction discriminator cfd shaping methods for use in the multichannel phenix lead scintillator detector has been investigated. Threshold adjust, 20mv to mv threshold monitor, 200mv to 10v. For that reason the constant fraction discriminator was created. In this work the design of a constantfraction discriminator cfd fabricated in the orbit. Parts of the investigated methods are variants of leadingedgediscriminators led and constantfractiondiscriminators cfd. In this way a signal that has a wide time variance using a leading edge discriminator can be narrowed. The output of the constant fraction discriminator cfd identifies the response of the detector and therefore should be considered as. Appendix a behavior of a constant fraction discriminator constant fraction discriminators cfd were used for pm3 and pm4 in order to reduce time walk. The constantfraction discriminator, arc timing, and other zerocrossing techniques are highly recommended for eliminating or minimizing walk.
However, it is more convenient for pspmts to use positive signals from the dynode for timing, because the signals share the dynodes and go to separate anodes, so we can consider using negative high voltage for the pmt. Constant fraction discrimination is a technique to provide amplitudeindependent information about arrival. This compact, rugged and lowpower instrument features two independent channels each with their own 0. Influence of rough surface on the ranging distribution of. The model 715 is a high performance, fivechannel constant fraction timing discriminator packaged in a single width nim module. The new readout electronics for the baf2calorimeter taps. Ultrafast laser spectroscopy is a spectroscopic technique that uses ultrashort pulse lasers for the study of dynamics on extremely short time scales attoseconds to nanoseconds. Positron annihilation lifetime spectroscopy pals report during the previous reporting period much progress has been made developing the pals research project. Measurements of timing resolution of ultrafast silicon detectors with. As i drink my beer, the amount of liquid in the bottle changes, but the amount of alcohol left in the bottle is a constant fraction of the amount of liquid left in the bottle.
How is constant fraction discriminator abbreviated. Design of a constant fraction discriminator for the. Two different values for the fraction in a constant fraction discriminator showing how the fraction depends on the delay delay cable plus internal delay and how time walk is virtually eliminated for signals of different amplitudes. Combine signals basic coincidence techniques discriminator a discriminator is a device which responds. Overview the lecroy model 3420 is a 16input constant fraction discriminator in a singlewidth camac module.
Appendix a behavior of a constant fraction discriminator constant fraction discriminators cfd were used for pm3 and pm4 in. The shaping delay circuit is made complete by connecting the appropriate cable length between two lemo connectors, allowing the user to optimize time resolution by easily matching the characteristics of each detector. In this paper, the theory of cfd method was analyzed in reality condition. A new, versatile, highperformance digital pulse processor. Constantfraction differential discriminatorsca the ortec model 583b constantfraction differential discriminator is a versatile, and highperformance unit suitable for the most exacting applications in timing spectroscopy. Three cfd circuits utilizing a distributed rc delayline, a lumpedelement rc delay line and the nowlin shaping method have been realized in a standard 1. The lowest energy at which ions will penetrate the 5vgcm2 carbon foil of the start seda of tof system is between 5 and 20 kev, and the lowest electronic threshold level on the signal of the solid state detector is 15 kev. General disclaimer one or more of the following statements. Pdf event detection methods for high resolution time. Different methods are used to examine the dynamics of charge carriers, atoms, and molecules.
A digital calorimetric trigger for the compass experiment. Implementation the digital cfd, calculates for each sample ithe difference d i between the signal s. Constantfraction discriminator good time resolution over a wide range of pulse amplitudes with scintillation and semiconductor detectors 50mhz countrate capability 5 mv minimum threshold time walk. Pdf se171 kapd9003e02 constant fraction discriminator mppc 001 s1036233050c s1036233 light dependent resistor constant fraction discriminator geiger apd constant fraction timing discriminator geiger tube geiger counter. The scanner is a gimballed mirror driven by stepper motors in elevation and azimuth. N605 4 channel 200 mhz constant fraction discriminator the n605 houses four independent 20% constant fraction discriminators cfd in 1unit wide nim. Tutorial on the ortec 935 quad constant fraction discriminator. Constant fraction discriminator cfd is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed timeofflight tof laser rangefinding. The constant fraction discriminators cfd8c, cfd7x, cfd4c. The signals from a given detector will typically have identical pulse shapes and a cfd utilizes this fact in order to provide a constant trigger point regardless of the signal amplitude. A discriminator produces an output logic pulse if its input signal exceeds a preset. A constant fraction discriminator cfd is an electronic signal processing device, designed to mimic the mathematical operation of finding a maximum of a pulse.
In this study i have chosen two largescale mergers, the merger of statoil and hydros oil and gas activities, and the failed attempt made by telenor and telia to merge their telecom activities. You own fractional shares in some company, and that company gets bought out as part of a merger with anoth. Constant fraction discriminator involving automatic gain. A fullintegrated pulseshape discriminator for liquid. When the numerator of a fraction is greater than or equal to the denominator, its called an improper fraction.
The typical energy resolution is 12 bit, and the timing resolution ranges to 65 ps rms. Constant fraction discriminator cfd technique is being investigated 36. Torre istituto nazionale di fisica nucleare infn sezione di pavia and dipartimento di fisica nucleare e teorica, universita% di pavia, via bassi 6, i27100 pavia, italy. Tutorial on the ortec 935 quad constant fraction discriminator kevin carnes fall, 2004. A constant fraction discriminator cfd is an electronic signal processing device, designed to mimic the mathematical operation of finding a maximum of a pulse by finding the zero of its slope. Ultrafast photon counting applied to resonant scanning. The differences between the two types of memory are also emphasized. Positron annihilation lifetime spectroscopy pals report. What happens to fractional shares as part of a merger on. Modify the software andor merge it into another program for your use on a single. Constant fraction discriminator zerocrossing disciminator. Graduate student brian wieland has been constructing, testing, and optimizing the experimental setup in preparation for two upcoming programs. Cfd is defined as constant fraction discriminator frequently.
This exercise will permit you to use the vmebus slave as if it was a piece of memory in your pc. It consists of a buffer, constant fraction discriminator cfd. Aiming effect of the rough surface on the pulse laser ranging distribution of constant fraction discriminator cfd, based on the traditional laser radar equation and rough surface characteristic, incoherent pulse laser detection equation of plane target is derived considering launch process as the shock response of linear system. Learn more about shibboleth at brown brown university. Pdf the constant fraction discriminator in pulsed timeof. The lecroy model 3420 is a 16input constant fraction discriminator in. A software framework has been developed to analyse the sampic output data and extract timing information by using either a constant fraction discriminator or a fast crosscorrelation algorithm. The ortec model 584 constantfraction discriminator allows good time resolution to be obtained from all commonly used detectors such as hpge, silicon chargedparticle, fast plastic, naitl, and photomultiplier tubes. Basic coincidence techniques a coincidence unit determines if two or more logic signals are coincident in time. Constantfraction discriminator how is constantfraction discriminator abbreviated. Triple constantfraction discriminator there is a common thresholdlevel pulse to all three nor diminished by increasing the size of rdsislac gates a deltafunction peak is obtained in the shape thereby slowing down the rise time of the thr lxst spectrum. Fully integrated currentmode cmos gated baseline restorer. The module accepts 8 negative inputs and produces 2.
Illustration of the summing network used to combine the input pulse. Reliability prediction of constant fraction discriminator. The integrated circuit ic will be called disc16c, short for discriminator chip 16 channels. Constant fraction discriminator cfd and tdc on same board crosstalk cfd depends on noise on single point, while waveform digitizing can average over several points inverter chain is same both in tdcs and scas can we replace tdcs by scas. A constant fraction discriminator 935, ortec, usa can be used to enhance the accuracy of photon arrival time.
Xu university of tennessee, knoxville a monolithic, cmos, constant hction discriminator cfd was fabricated in the orbit semiconductor, 1. These logic pulses are passed to an ortec 567 tac gated by an ortec. Figure 2 illustrates the process used to produce this trigger at a. The design, simulation and printedcircuitboard pcb performance of cfd circuit were shown. When operated in the differential mode, the model 583b is ideal for use with fast scintillators and photomultiplier tubes.
Triple constantfraction discriminator sciencedirect. Constant fraction discriminator cfd, and two chargeintegrating adcs qdc, as well as a timetodigitalconverter tdc. The reasoning behind separate bc blocks was that the digital shaper ds. Brown university authentication for webbased services. The ortec model 584 constant fraction discriminator allows good time resolution to be obtained from all commonly used detectors such as hpge, silicon chargedparticle, fast plastic, naitl, and photomultiplier tubes. Investigation of the time performance of a lyso array for tofpet. Fast constant fraction differential discriminator for positron lifetime spectroscopy 99 since the life time components are in the range of 160 ps up to few nanoseconds, it is necessary to provide an as good as possible temporal resolution 5, for the experimental setup.
This will demonstrate that from the programming point of view there is very little difference between internal and external memory. N842 is an 8 channel constant fraction discriminator housed in a one unit wide nim module. Constant fraction discriminator involving automatic gain control to reduce time walk article in ieee transactions on nuclear science 614. Cf constant fraction attenuation factor is internally set at f 0. User manual hrmcfd programmable constant fraction discriminator sensl 2011 1 2channel, usb, programmable cfd module the sensl hrmcfd provides a. Integrated constantfraction discriminator shaping techniques. Many different procedures have been developed spanning different time scales and photon energy ranges. Integrated receiver channel and timing discrimination. This definition appears frequently and is found in the following acronym finder categories. Discriminators generate precise logic pulses in response to input signals exceeding a given threshold.