|The SR430 is the first multichannel scaler which combines amplifiers, discriminators, bin clocks, and data analysis in a single, integrated instrument. With its many features and its easy-to-use menu driven interface, the SR430 simplifies time-resolved photon counting experiments.|
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The SR430 is the first multichannel scaler which combines amplifiers, discriminators, bin clocks, and data analysis in a single, integrated instrument. With its many features and its easy-to-use menu driven interface, the SR430 simplifies time-resolved photon counting experiments.
The SR430 Multichannel Scaler/Averager can be thought of as a photon counter that counts events as a function of time. A trigger starts the counter which segments photon count data into sequential time bins (up to 32k bins). The width of the bins can be set from 5 ns to 10 ms. The instrument records the number of photons that arrive in each bin.
The SR430 is useful in a variety of applications where it is necessary to count events as a function of time: LIDAR, time of flight mass spectroscopy, and fluorescence decay measurements are just a few examples.
Input and Discriminator
The SR430s analog input has a 50 Ω input impedance and an input range of ±300 mV. The maximum input sensitivity is 10 mV, and if your input signal level is less than this a preamplifier (like the SR445) should be used. The input is followed by a discriminator with a selectable slope and a threshold adjustable between ±300 mV. A discriminator BNC output is provided at the front panel that generates a NIM level (0-.7 V, active low) signal corresponding to each count.
A trigger pulse starts the data acquisition cycle. The SR430 offers a choice of bin widths ranging from 5 ns to 10.486 ms. Alternatively, an external bin clock can be provided to the SR430, allowing you to define your own bin size.
The number of bins in each record is adjustable from 1k (1024) to 32k in 1k increments. Data acquisition in the SR430 is seamlessthere is no dead time between bins. Once the selected number of bins has been recorded, the SR430 either adds or subtracts the result of the current record from the accumulated bin totals.
The SR430 can be programmed to accumulate between one and 64k records, or set to free run. Each record can be added or subtracted from the current accumulator totals. The instrument can be set to toggle between add and subtract every N records, or an external toggle input can select the polarity of the next record. A rear-panel inhibit input allows you to selectively prevent the accumulation of any given record. The screen display is updated continuously as records are accumulated, providing a live, real-time display of the data.
The 7" CRT screen allows complete flexibility in displaying your results. Between 8 and 16k bins can be displayed on the screen at any time, and complete horizontal and vertical zooming and scrolling features are provided. An "Autoscale" key quickly optimizes the screen for the current data with a single keypress. A fast, responsive, on-screen cursor lets you read the maximum, minimum or mean data value from a selected range of the graph.
Menus and Softkeys
The SR430 is based on a simple, menu-based user interface. Each menu groups related instrument functions and defines softkeys to control those functions. The instrument settings are changed by pressing the softkeys or by turning the front-panel knob. Complete context sensitive help is provided for all menus and softkeys. The remote command list is also provided on a help screen as an aid in programming the SR430.
The SR430's extensive capabilities don't stop with data acquisition. Savitsky-Golay smoothing can be applied to any portion of the data, with selectable smoothing intervals. Gaussians, exponentials or straight lines can be fit to arbitrary regions of the display, allowing you to quickly determine decay lifetimes. Basic statistical parameters can be calculated for data regions including total number of counts, mean number of counts, and variance. Basic arithmetic operations, including addition, subtraction, multiplication, division, logs and square roots, can be applied to the current data.
Built-In Disk Drive
The SR430 has a built-in 3.5" DOS-compatible disk drive to simplify data transfer between the instrument and your computer. Both data files and settings files can be stored so you can save complete instrument setups for a variety of situations and recall them instantly.
Hardcopy output is available from the SR430 in a variety of forms. A standard Centronics printer port lets you dump the screen to dot-matrix or LaserJet compatible printers at any time. Additionally, the SR430 can plot its display on any HP-GL compatible plotter via the RS-232 or GPIB interface.
Both RS-232 and GPIB interfaces are standard on the SR430 ensuring compatibility with the widest range of laboratory computers. All instrument settings and functions can be read and set via the interfaces. A complete list of all characters received and transmitted over the interfaces can be displayed on the CRT screenan invaluable aid when debugging your programs. Numerous modes are available for downloading the count data to your computer including ASCII transfer, binary transfer, and a fast binary dump mode which transfers data continuously over the GPIB interface as it is being acquired by the instrument.