Multichannel Scaling Research Articles

Bi-implanted silicon reference material revisited: uniformity of the remaining batch

A remaining batch of 65 samples of the Bi-implanted silicon reference material, issued earlier by our institution, has been investigated extensively with respect to the uniformity of the implanted Bi-layer. For this purpose long-time RBS measurements were performed in the multichannel scaling (MCS) mode. The determined non-uniformity expressed as the relative range of the bismuth fluence between its maximum and minimum values is 7%. The relative amount of the Bi fluence in individual chips as presented in this paper serves as basis to assign individual calibration values to each implanted chip. Furthermore, an estimate of the uniformity within each sample can be based upon the acquired MCS data.

A MacintoshTM-based multiparameter pulse height analyzer and multichannel scaler system for advanced teaching laboratories

A low‐cost, moderately high‐speed Apple MacintoshTM‐based data acquisition and analysis system has been developed based on a low‐cost National Instruments■ NuBus TTL interface card with external Nuclear Instruments Module analog‐to‐digital converters. Features of the system include multiparameter coincident pulse height analysis and multichannel scaling in a user‐friendly graphical user‐interface environment of data windows, pull‐down menus, and multiparameter gating. This system has been effectively used for nuclear, atomic, and modern physics experiments in the advanced undergraduate laboratory courses at the University of Michigan. It offers a cost‐effective solution for numerous data acquisition needs.

A front—End data acquisition system for Mössbauer spectroscopy

A front—end data acquisition system based on STD BUS for Mossbauer spectroscopy is described. The system operates in both pulse height analysis and multichannel scaling with high resolution and allows pre—processing or filtering of the data. With the system, many kinds of computer and/or microcomputer can easily read out Mossbauer experiments data on real time via a standard interface. The many features of opening architecture is based on the industral control standard bus (STD BUS) managed by Z80 processor in the system are exposed in the paper. This architecture is able to build up flexible and expanable data acquisition system. Both a survey of the system hardware capability and a presentation of the sys tem software are exhibited as well.

5nsec Dead time multichannel scaling system for Mössbauer spectrometer

A PC programmable and fast multichannel scaling module has been designed to use a commercial Mossbauer spectrometer. This module is based on a 10$ single chip 8 bits microcomputer (MC6805) and on a 35$ fast ALU, which allows a high performance and low cost system. The module can operate in a stand-alone mode. Data analysis are performed in real time display, on XT/AT IBM PC or compatibles. The channels are ranged between 256 and 4096, the maximum number of counts is 232−1 per channel, the dwell time is 3 μsec and the dead time between channels is 5 nsec. A friendly software display the real time spectrum and offers menues with different options at each state.

The use of a multichannel scaling method to detect radioactive species in spread monolayers

This study describes a simple and inexpensive method for monitoring radioactive species spread as monolayers at the air/water interface. The combination of a discriminator and multichannel scalar counter with a personal computer functions to unify all measurements, to simplify the operational process and data acquisition, and to provide a real-time display of the data. Its use is demonstrated by following the hydrolysis of l-α-[1- 14C]dioleoyl phosphatidylcholine by the enzyme, phospholipase A 2, isolated from the porcine pancreas.

An inexpensive microprocessor-controlled multichannel scaling system for in vivo radiotracer studies

A multichannel scaling (MCS) system has been developed to monitor the biological distribution of radiotracers in vivo. The design of this system permits the simultaneous collection of data from up to four radiation detectors. The evolution of detected count rates is displayed in real time as a histogram with a minimum channel width of 1 s. Each point in the data arrays can accommodate more than 16 million counts. The low-power Schottky integrated circuits used can readily process the maximum count rates that sodium iodide detectors can produce. The four counting units together with control circuitry were constructed on a single custom IBM PC expansion board.

A fast microprocessor controlled data acquisition system for high resolution Mössbauer spectroscopy

We describe a microprocessor controlled data acquisition system designed for Mossbauer spectroscopy which operates in both pulse height analysis and multichannel scaling with high counting rate (> 20 MHz) and resolution (up to 8192 channels per spectrum). The apparatus makes use of two counters and of a double memory block. It is thus possible to obtain a minimum channel-advance dead-time lower than 50 nsec and a minimum dwell-time of 1 μsec. The accumulated data are transferred to a microcomputer for storage and analysis from one of the two blocks while the other continues the acquisition process. The system is totally programmable, and all the acquisition parameters can be easily selected in a wide range.

Photoion-photoelectron coincidence spectroscopy of the transient molecules SO and S 2O

Photoion-photoelectron coincidence (PIPECO) spectra, in the wavelength range of 1025–1210 Å, for SO and S 2O formed in a microwave discharge of SO 2 have been measured using a pulsed PIPECO method. Vibronic bands attributable to the formation of SO + (X̃ 2Π 3/2,1 2 , ν=0−11), S 2O + (X 2A′, ν′=0−2), and S 2O + ( 2A′, 2A″,ν′=0−3) are resolved in the SO + and S 2O + PIPECO spectra. The spin-orbit splitting for SO + (X̃ 2Π) is determined to be 371±20 cm −1. The ionization energies for SO and S 2O obtained from photoionization efficiency measurements are 10.294±0.004 eV (1204.4±0.5 Å) and 10.584±0.005 eV (1171.4±0.5 Å), respectively. The pulsed PIPECO method used in this experiment is superior in both sensitivity and resolution compared to the continuous multichannel scaling PIPECO scheme.

Computer systems in microscopy: The big, the small and the ugly

The transmission electron microscope has now reached a stage of maturity such that the differences between different models are in the details rather than the fundamental design. Although the early computer systems in microscopy appeared only as adjuncts to X-ray multichannel analyzers newer, more powerful systems have become available at relatively low cost and there is an increasing demand for image acquisition, processing and analysis. There is still no agreement as to what is the right design for a microscope computer system. The answer depends not only on the planned applications but also on the organization of the microscopy lab.For spectroscopy there is a need to acquire spectra both by multichannel scaling (EELS) and multichannel analysis (EDX) and process the results for quantitative analysis. In imaging the requirement can be for either capture of TV camera images or direct scanning of a focussed probe across the specimen with digitization of an appropriate signal (bright field, secondary electron).

An intelligent, computer-independent multichannel scaler

An inexpensive multichannel scaler is described which incorporates a dedicated 6502 microprocessor. The instrument may be interfaced to any computer with an RS232 serial port, and is intended to relieve powerful mini- and microcomputers of the mundane tasks associated with multichannel scaling. The new instrument allows the supporting software to control all the parameters associated with the acquisition of data. It is also capable of performing functions that have previously been impossible with conventional multichannel scalers. The instrument has been successfully applied to a number of high resolution electron impact spectrometers, principally to investigate the excited states of gaseous atoms and molecules.

Microcomputer interface board for time-resolved multichannel scaling

A low-cost multichannel scaler and signal-averaging system with user selectable channel widths ranging from 1 to 255 μs has been developed for molecular beam time-of-flight (TOF) experiments. It has the ability to collect up to 255 channels and has a programmable delay of up to 0.65 s. On-board logic can accommodate a 15-MHz count rate. Completely contained on a 7×2 3/4 -in. Apple II prototyping board (with the exception of a 5-A, 5-V external power supply), the interface fits into a peripheral port of the Apple II. The interface was tested by measuring the TOF distribution of Ar metastables from a supersonic nozzle beam source.

Measurement of the15N(n,p)15C cross section from 14 TO 15 MeV

Abstract The N-15(n,p) C-15 cross section between 14.6 and 15.0 MeV was measured, using activation analysis of a CINH4 sample with 10% enrichment in N-15. The efficiency of the detection system for the C-15 gammas (5.299 KeV) was determined using rays from S-37 and N-16. The flux incident on the sample was controlled with the N-14 (n,2n)N-13 and C1–37(n,p)S–37 reactions, with corrections for C1-35(n,2n) C1-34g interference. The C-15 induced activity was observed with multichannel scaling, allowing a determination of the half life too. The results are [sgrave] = 26.5±12mb; t± = 2.42±0.16s.

A fast data acquisition system for PHA and MCS measurements

A microprocessor controlled data acquisition system for pulse height analysis and multichannel scaling is described. A 4K×24 bit static memory is used to obtain a fast data acquisition rate. The system can store 12 bit ADC or TDC data within 150 ns. Operating commands can be entered via a small keyboard or by a RS-232-C interface. An oscilloscope is used to display a spectrum. The display of a spectrum or the transmission of spectrum data to an external computer causes only a short interruption of a measurement in progress and is accomplished by using a DMA circuit. The program is writtenin Modular Pascal and is divided into 15 modules. These implement 9 parallel processes which are synchronized by using semaphores. Hardware interrupts from the data acquisition, DMA, keyboard and RS-232-C circuits are used to signal these processes.

Exact solution of the multichannel Kondo problem, scaling, and integrability

In this work we give the exact solution of the model describing the scattering of conduction electrons by an impurity in the orbital singlet state (so-calledn- channel Kondo problem). Depending on the relation between the impurity spinS and the number of electron scattering channelsn, the model behaves differently at low energies. At ⩽2S the effective charge increases to infinity at low energies, whereas atn > 2S it tends to a finite fixed point. The model under study is the first example of the one-dimensional quantum field theory exhibiting scaling behavior.

Application of on-Line Laboratory Computer Analysis to Fast Neutron Activation Oxygen Determinations

The development of an on-line laboratory computer analysis system designed for routine high volume oxygen determinations is discussed. The system is based on the detection of 16N photopeaks from the 16O(n,p)16N reaction occurring during fast neutron irradiation. A system interface has been designed and constructed which is capable of controlling the Kaman 710 neutron generator, the sample transfer system, switching the BF3 beam monitor detector or NaI(Tl) detector outputs as required to a multichannel scaling MCA, and proper sequencing of the procedure. In addition, specific software has been developed for the control of the system during acquisition as well as evaluation of the MCS spectra generated.

High-resolution field-desorption mass spectrometry utilizing multichannel scaling techniques

The use of a Tracor—Northern Model 1700 multichannel analyzer operated in the multichannel scaling mode has been shown to simplify greatly the acquisition of high-resolution field-desorption mass spectra for very high masses (>1000 daltons). The data are acquired using voltage scanning, and an equation is derived which converts the masses obtained by linear interpolation into true mass values.

Simple low-cost digital events analyzer

We present the design and applications of a simple and very low-cost digital events analyzer, suitable for use in a student laboratory as well as in research applications. The pulse analyzer can perform five functions: sampling measurement; pulse interval distribution measurement; simple triggered multichannel scaling; scaled triggered multichannel scaling; and auto- and cross-correlation function measurement. The memory capacity is limited to 100 channels with 11 bits or more word length. The basic cycle time of the analyzer is 500 ns as limited by the speed of MOS circuit used. We demonstrate the utility of it with counting statistics experiments of radiations from radioactive decay, neutron time of flight analysis, and also the photon correlations measurements of light scattered from particles in fluids.

A FORTRAN program to perform signal averaging, multichannel scaling, and pulse-height analysis

A FORTRAN program to perform signal averaging, multichannel scaling, and pulse-height analysis

Multichannel scaling with an eight bit microcomputer

In this note a microcomputer-based system for multichannel scaling is described. This system relies on a combination of simple hardware with software support to achieve maximum cost effectiveness.

A seven channel gated charge to time converter

By using a hybrid integrated circuit seven independent gated charge to time converters have been constructed in a single width NIM module. Gate widths from ⪅10 ns to ∼300 ns are possible with a resolution of 0.25 pC, linearity is better than ±1 pC over 2.5 decades of input signal height. Together with a multichannel scaling system described in the following paper one has a very powerful multichannel gated ADC system.