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. One of the components, constant fraction discriminator, is the critical part at which the failure phenomenon and modeling by regression is studied in this paper using physics of failure methodology. Development of a nondelay line constant fraction discriminator based on the pade approximant for timeofflight positron emission tomography scanners. Gottschalk timing discriminator 10 ns for a range of risetimes and amplitudes giving a leadingedge walk of 350 ns. Brown university authentication for webbased services. Typical time walk plus input slewing of 75psec is achieved for inputs from threshold to 100 times threshold. Integrated constantfraction discriminator shaping techniques. As the number of readout channels increases, it becomes difficult to use conventional cfds because of the large amount of space required for the delay. The flexible ortec cf8000 octal constantfraction discriminator has the performance and convenience features necessary for ease of use in even the most demanding timing or coincidence experiments with multiple detectors. The design, simulation and the pcb performance of the cfd circuit were shown. 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. Simulations show that it is possible to extend the frontend shaping time in order to fully integrate the gem detector signal charge whilst maintaining optimal timing resolution using the cfd. The suitability of several onchip constantfraction discriminator cfd shaping methods for use in the multichannel phenix lead scintillator detector has been investigated.
In distributed computing, a discriminator is a typed tag field present in omg idl discriminated union type and value definitions that determines which union member is selected in the current union instance. The time resolution, which is an important parameter for the use of the gem. Cfd is defined as constant fraction discriminator frequently. Design of a constant fraction discriminator for the vfat3 frontend asic of the cms gem detector view the table of contents for this issue, or go to the journal homepage for more. 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. Some signals do not have a sharp maximum, but short rise times. 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. Timing discriminator using leadingedge extrapolation. Pdf constant fraction discriminator cfd is one of theoretic method which can locate timing point at same fraction. It is called the differentiation constant fraction discriminator. The constant fraction discriminators cfd8c, cfd7x, cfd4c. A constant fraction discriminator cfd is an electronic signal processing device, designed to.
Tutorial on the ortec 935 quad constant fraction discriminator. Unlike in some conventional programming languages offering support for unions, discriminator in idl is not identical to selected field name. Triple constantfraction discriminator sciencedirect. This shows how the input signal is split, one half attenuated. Coherent electronicvibrational dynamics in deuterium bromide probed via attosecond transient absorption spectroscopy. Pdf the constant fraction discriminator in pulsed timeof. Design of a constant fraction discriminator for the vfat3 frontend asic of the cms gem detector. In this work the design of a constant fraction discriminator cfd to be used in the vfat3 chip, currently under design for the readout of the triplegem detectors of the cms experiment, is described. The vertical scale is logarithmic and the horizontal scale is 1 ms.
Sensor and micromachined optical device technologies, 81911f 8 september 2011. In this way a signal that has a wide time variance using a leading edge discriminator can be narrowed signi. 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. In this paper, the theory of cfd method was analyzed in reality condition.
Pdf development of a monolithic constant fraction discriminator. The constant fraction discriminator in pulsed timeofflight. The constant fraction discriminators cfd8c, cfd7x, cfd4c, cfd1c and cfd1x 11. Apr, 2012 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. Positron annihilation lifetime spectroscopy pals report. The choice among one or another realization of constant fraction discriminator cfd 1 or double fraction discriminator dfd 2 has to be done. Learn more about shibboleth at brown brown university. 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. One front panel output provided both as a nim signal via a lemo connector and as an ecl differential level 0. The constant fraction discriminator in pulsed timeof.
The ortec model 584 constantfraction discriminator allows good time resolution to be obtained from all commonly used detectors such as hpge, silicon. The sixteen channel camac constant fraction discriminator. Pdf fast constant fraction differential discriminator for positron life. Instruments firmware download for lockin amplifier and noise rejecting voltmeter, installation programs and instruction sheets by model number and firmware version. Measurements of timing resolution of ultrafast silicon detectors with. Design of a constant fraction discriminator for the. A method for reducing excessive constant fraction discriminator walk that utilizes experimental data in the offline analysis stage is introduced. A monolithic, cmos, constantfraction discriminator cfd was fabricated in the orbit semiconductor, 1. Without the linearity correction that is, with it i2 the walk is 30 ns for the ranges of sizes and shapes shown. Some signals do not have a sharp maximum, but short rise times typical input signals for cfds are pulses from plastic scintillation counters, such as those used for lifetime measurement in positron. Constant fraction discriminator in pulsed timeofflight. 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. A constant fraction discriminator was developed with a bipolar applicationspecific ic asic technology from nec without a delay.
The model 6915 is a high performance, single channel constantfraction timing discriminator. The design, simulation and printedcircuitboard pcb performance of cfd circuit were shown. 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. Pdf format for this model number or go to our download area where all the data. A prototype chip containing 8 cfds was implemented using. In positron emission tomography, the constant fraction discriminator cfd circuit is used to acquire accurate arrival times for the annihilation photons with minimum sensitivity to time walk.
The constant fraction discriminator alleviates this problem by using a constant fraction, of the input pulse to precisely determine the timing of the output pulse relative to the input signal. Digital timing in positron emission tomography core. This is the input pulse used for simulating the operation of the ortec 935. Model 7029a constant fraction differential discriminator. A method for reducing excessive constantfractiondiscriminator walk that utilizes experimental data in the offline analysis stage is introduced.
The suitability of several onchip constant fraction discriminator cfd shaping methods for use in the multichannel phenix lead scintillator detector has been investigated. The simplest solution to digital timing is implementing the digital equivalent of the constant fraction discriminator cfd. The sixteen channel camac constant fraction discriminator for apex. Constant fraction discriminator for fast highprecision. The constant fraction discriminator cfd has been used for many years because of its negligible time walk 1234, and a theoretical analysis was done by. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. In the design fso system, the pamu provides to monitor transmitted and received. Discriminators generate precise logic pulses in response to input signals exceeding a given threshold. Mexico cfd community facilities district cfd cheyenne frontier days. N843 is an 16 channel constant fraction discriminator housed in a one unit wide nim module.
It contains eight constant fraction discriminators in a singlewidth nim module. Constant fraction discriminator cfd is one of the theoretic method which can locate the timing point at same fraction of the echo pulse in pulsed timeofflight tof laser rangefinding. Constantfraction discriminator how is constantfraction. The delayline is constructed from a narrow, 500mu serpentine layer of polysilicon above a wide, grounded, second layer of polysilicon. Spie 8191, international symposium on photoelectronic detection and imaging 2011. These logic pulses are passed to an ortec 567 tac gated by. This circuit uses an onchip, distributed, rc delayline to realize the constant fraction shaping. Its small rugged packaging makes it ideal for mounting nearby the detector often in remote locations. Citation download citation jianyong chen, dongqing shen, and wancai li constant fraction discriminator for fast highprecision pulsed tof laser rangefinder, proc. Tutorial on the ortec 935 quad constant fraction discriminator kevin carnes fall, 2004.
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. How is constant fraction discriminator abbreviated. This definition appears frequently and is found in the following acronym finder categories. Overview the lecroy model 3420 is a 16input constant fraction discriminator in a singlewidth camac module. The cfd timing discriminator modules the roentdek cfd constant fraction discriminator units can be used for improving the timing response of electronic. Pdf the constant fraction discriminator in pulsed time. It contains eight constantfraction discriminators in a singlewidth nim module. 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. Development of a monolithic constant fraction discriminator.
Signal processing for picosecond resolution timing measurements. Noise contribution to timing with fraction discriminators. Pdf the constant fraction discriminator in pulsed timeofflight. Acronym definition cfd computational fluid dynamics cfd contract for difference marketstrading cfd child and family development cfd center for dance various locations cfd complement factor d aka adipsin. Figure 2 illustrates the process used to produce this trigger at a. There are two main types of discriminators, the leading edge discriminator and the constant fraction discriminator. One of the components, constant fraction discriminator, is the critical part at which the failure phenomenon and modeling by regression is studied in this paper using physics of. This circuit uses an onchip, distributed, rc delayline to realize the constantfraction shaping. Design of a constant fraction discriminator for the vfat3. The sixteen channel camac constant fraction discriminator for.
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 model 715 is a high performance, fivechannel constant fraction timing discriminator packaged in a single width nim module. It does this by splitting the input signal figure 2. Cf8000 octal constantfraction discriminator fast timing. The flexible ortec cf8000 octal constant fraction discriminator has the performance and convenience features necessary for ease of use in even the most demanding timing or coincidence experiments with multiple detectors. A monolithic, cmos, constant fraction discriminator cfd was fabricated in the orbit semiconductor, 1. Ab in this work the design of a constant fraction discriminator cfd to be used in the vfat3 chip for the readout of the triplegem detectors of the cms experiment, is described. Threshold adjust, 20mv to mv threshold monitor, 200mv to 10v.
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