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The MCA-8000A is a full featured, low power multichannel analyzer for use with a wide variety of detector systems. The easy to use 'Pocket MCA' can fit in a shirt pocket.
The Amptek MCA8000A ‘POCKET MCA’ is a state-of-the-art, compact, low power Multichannel Analyzer (MCA) with the high performance found only in much larger systems. From 20 years of experience in building scientific spacecraft instrumentation, Amptek has developed specialized, high density circuitry that gives the MCA8000A a significant advantage over other MCAs. All that is needed to operate the MCA8000A is a computer with a standard RS-232 serial interface.
Superior performance results from a sophisticated low-power peak hold circuit (Amptek PH300) followed by a 16 bit analog to digital converter with sliding scale linearization. Spectra are accumulated in nonvolatile memory and read out by a microcontroller. Advanced power management techniques maximize battery life.
The POCKET MCA gives the performance necessary for semiconductor detectors such as HPGe, Si and CdTe/CZT. At the same time, it provides the portability needed in the field. The user friendly software included with the MCA8000A allows the acquisition, display, calibration and manipulation of spectra in both DOS and Windows environments.
Compromising nothing in performance, the MCA8000A is a low power, light weight instrument that is exceptionally versatile and easy to use. Ideal for laboratory work, OEM applications, and portable instrumentation.
| PULSE-HEIGHT DIGITIZER | Successive-approximation ADC with two stage input analog pipeline and sliding-scale linearization. Software selectable resolution: 16k, 8k, 4k, 2k, 1k, 0.5k, 0.25k channels. The sliding scale linearization technique reduces the ADC range by 1/32. |
| PULSE PROCESSING TIMES | Minimum pulse peaking time is 250 ns. Acquisition time of the analog pipeline <,=2 µs. ADC conversion time <,=5 µs. |
| PEAK DETECTION MODES | First Peak After Threshold (V1): Standard to nuclear instrumentation MCAs Absolute Peak Above Threshold (V2): Typically used in airborne particle sizing analyzers, in environmental air monitoring systems, and in aerosol research. See Option PA to further facilitate airborne and suspended particle sizing.
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| DIFFERENTIAL NONLINEARITY | <±0.6% from 15 mV to full scale. |
| INTEGRAL NONLINEARITY | <±0.02% over full scale. |
| GAIN STABILITY | Gain <±10 ppm/°C; Zero drift <±3 ppm/°C. |
| LOW LEVEL DISCRIMINATOR | Software selectable threshold, in increments of one channel, up to half of full range. Threshold accuracy <±0.5% of full range. |
| MEMORY | Nonvolatile, 10 years data retention. The memory is segmented and can store up to 128 different spectra. The number of the groups available depends on the ADC resolution and is given as: 32k/[ADCRESOLUTION]. |
| MAXIMUM COUNTS PER CHANNEL | 4.29 x 109 counts (4 bytes). |
| TIMERS | Real and Live Timers. Data acquisition real or live time preset in multiples of one second. Maximum preset time 16777215 (224 - 1) seconds. Shorter or non-integer acquisition times can be achieved by gating the input signal with Gate 1 or Gate 2. Every time a data acquisition is started a start time-date stamp is stored in the current memory group. |
| INTERFACE | RS-232 Serial, high speed 115.2 kbps. Software selectable baud rate selection: 4.8 kbps, 9.6 kbps, 19.2 kbps, 38.4 kbps, 57.6 kbps, 115.2 kbps. |
| SECURITY | Each MCA8000A unit is assigned a unique serial ID number that is hardwired and is accessible through the computer software. A five digit MCA lock number can be used to lock data in the internal memory. Zero lock number disables the security feature. |
| OPERATING TEMPERATURE | 0-70°C. |
| POWER: | Power is turned on either by a computer or by a power switch. The MCA8000A has an automatic power-down function when operating on battery power which turns the power off whenever the MCA is not acquiring data or exchanging data with a computer. If the MCA is powered via an external power adapter or the data acquisition is active while on battery power, the automatic power-off function is disabled. |
| Operating Power | <300 mW in data acquisition mode with active serial interface, <250 mW in data acquisition mode with inactive serial interface (stand-alone mode). |
| Power sources | Two AA batteries or 9 V (200 mA) AC adapter (included) 3.5mm x 1.3mm Female Barrel; Center positive. When operating on external power via the adapter, there is no drain or recharging of the internal batteries. |
| Battery types | Any type of AA battery, including: alkaline, Lithium, rechargeable NiCad or NIMH, or any battery set with appropriate capacity and voltage range from 2 to 7 V. |
| Protection | Built-in protection against incorrect battery polarity. |
| Power monitor | Battery discharge monitor for alkaline and NiCad batteries. |
| Battery life (typical) | From a set of two alkaline batteries - 24 hours in stand-alone acquisition mode with inactive serial port, 16 hours in acquisition mode with active serial port. |
| ON/OFF BUTTON | ON/OFF button toggles the MCA8000A power between ON and OFF |
| STATUS LIGHT | Steady red light indicates that the MCA power is ON and no data acquisition in progress. Flashing red light indicates MCA is in data acquisition mode. |
| INPUT RANGE SWITCH | Switch sets the dynamic range of analog input pulses at 0 to +5 V or 0 to +10 V. |
| INPUT | The analog input accepts positive unipolar or bipolar semigaussian type pulses of shaping time constants >,=100 ns (peaking time >,=250 ns). See examples below. The dynamic range is 0 to +5 V (Zin = 200 kohm) or 0 to +10 V (Zin = 2 kohm), selectable by the Input Range Switch. The input has overload protection up to ±15 V. The DC level of the input signal must be set to zero. The minimum input signal for the specified nonlinearity is 15 mV. |
| GATE 1 | Active HIGH TTL compatible logic gate. When this input is HIGH, the analog input pulses are gated off and the live clock is stopped. The active state of this signal must occur at or prior to the peak of the analog pulse and must extend for at least 1 µs after the peak. When not connected, this input is held inactive by an internal pull-down resistor. |
| GATE 2 | Active LOW TTL compatible logic gate. When this input is LOW, the analog input pulses are gated off and the live clock is stopped. The active state of Gate 2 must occur at or prior to the peak of the analog pulse and must extend for at least 1 µs after the peak. When not connected, this input is kept inactive by an internal pull-up resistor. |
| INTERFACE (I/O) | DB-9 male RS-232 connector. This connector requires a null modem cable (included) to connect to a computer (min requirement Pentium 200+). The MCA8000A requires a full RS232 port. USB to RS232 converters do not work. See operating notes below. |
| POWER | The MCA8000A power connector mates to a center positive, 3.5 mm x 1.3 mm female barrel connector. |
NOTE: The input to the MCA8000A must be a positive going unipolar or bipolar shaped pulse of peaking time greater than 250 ns.
 Example of unipolar input pulse |
 Example of bipolar input pulse |
| WEIGHT | < 300 g (including set of alkaline batteries). |
| DIMENSIONS | 6.5" x 2.8" x 0.8" (165 x 71 x 20 mm) |
The MCA8000A connects to any host computer (min. Pentium 200+) via an RS-232 serial interface. The baud rate is software selectable and set by the computer. Display software is included. The data exchange protocol is available to the user to facilitate custom connections to other computer platforms.
Some new laptop/notebook computers do not come with RS-232 ports. In these cases, Amptek recommends the use of a PCMCIA RS-232 card for use with the MCA8000A. These Serial Port PC cards can be found online. One example is manufactured by Quatech. Because of the complexity of the MCA8000A communication protocol, "USB to Serial" converter cables do not work well.
Key parameters in the MCA8000A data acquisition configuration are the low level threshold and the data acquisition time. The low level threshold is digitally set and stored in the nonvolatile memory. The acquisition time can be preset as either live or real, since the MCA8000A has both real and live time clocks. The live time clock adjusts for deadtime by turning off the clock whenever: a) the input signal exceeds the low level threshold, b) the analog pipeline is holding a pulse to be processed by the ADC, or c) if one or both of the MCA gates are active.
The successive approximation ADC digitizes the pulse amplitude in less than 5 µs. If a second pulse arrives while another pulse is being processed, it is held by the internal peak-hold detector. The second pulse is processed after the ADC has completed digitizing the first pulse. Because of this two stage storage, the dead time following a single pulse can be as short as 2 µs. The use of the sliding scale technique maintains differential nonlinearity to better than ±0.6% over full scale.
The MCA8000A can operate in a stand-alone mode, not connected to any host computer. The MCA8000A enters this mode after data acquisition is activated by the host computer and then the host computer is either turned off or disconnected from the MCA8000A. In this stand-alone mode, the MCA will acquire data until the preset acquisition time (real or live) is reached.
Once the spectrum is acquired, the MCA waits approximately 2 minutes for a connection with the host computer. If there is no connection attempt from the host computer, the MCA8000A powers down with the spectrum stored in memory.
The MCA8000A can store spectra in up to 128 different memory groups. Each group also stores the data acquisition parameters and the time-date stamp. All spectra can be held in the MCA8000A memory for up to 10 years. This capability is provided by low power memory backed by an internal Lithium battery.
Upon reconnection to the host computer, the spectrum is transferred and displayed. As a result, the MCA8000A provides easy and reliable transport of spectral data from one place to another - all that is required is a serial connection to a computer.
The PMCA Software allows data acquisition and display on any PC compatible computer, including desktops, notebooks, and palmtops. The computer should be a Pentium 200 or greater. This software supports region of interest (ROI), energy calibration, peak search, peak information, MCA8000A configuration, multiple spectra, and mathematical operations.
The PMCA Software acquires and displays all data transmitted by the MCA8000A: spectral data, elapsed real and live time, and status parameters and flags, including battery status.
Among the primary tools in PMCA Software is an automatic peak search routine which marks the identified peaks as ROIs. Peak counts and FWHM are automatically calculated and displayed in either channels or user-defined calibration units.
The Windows version of the PMCA Software includes an isotope library and listing of atomic x-ray emission lines. The peak information panel automatically suggests the isotope or x-ray line closest to the peak. Multiple spectra can be displayed at the same time and mathematical operations can be performed on the spectra. Examples of the Windows software are shown in Figures 3 and 4.
Figure 3. PMCA Windows Software showing Regions of Interest (ROI)
Figure 4. PMCA Windows Software showing multiple spectra capability
In order to accommodate custom applications, a complete Application Programming Interface (API) capable of performing the functions of the MCA8000A is included. These libraries (.dll and .lib) will link directly with the customer-written code to control the MCA8000A.
Utilizing the libraries above, an example program written in Visual Basic has been provided to aid in the characterization of x-ray tubes. This routine automatically saves a complete spectrum at user defined intervals, and in addition produces a file consisting of the total counts in each spectrum. This total counts file can then be plotted in Excel. The program can be used in any application where data need to be taken on a timed basis.
 Input Side of MCA8000A |  Control Side of MCA8000A |
Option PA is NOT recommended for standard nuclear instrumentation applications. It is for use only in airborne and suspended particle applications.
MCA8000A Specifications in PDF format (865 k)
Glossary
Revised September 26, 2006
