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Bridgeport Instruments, LLC, 11740 Jollyville Rd., Ste 500, Austin, TX 78759,
www.BridgeportInstruments.com
Summary
The MCA-3000 is a family of high-performance multi-channel analyzers (MCA) for measuring
gamma-ray radioactivity with a scintillator.
The PMT-3000 includes a operating voltage supply and plugs directly onto a photomultiplier.
The SiPM-3000 includes the SiPM operating voltage supply and plugs directly onto an SiPM-array.
Using its embedded 32-bit ARM processor, it provides accurate gamma-ray spectroscopy and gain
stabilization together with many advanced features such as automatic background subtraction and
alarm computations.
This document describes how to use the MCA-3000 from the graphical user interface and from
Python scripts. Using the MCA Data Server, developers will find they can program the MCA-3000
in any language they want.
Feature summary – PMT-3000
More than 4Mcps histogramming rate
Suitable for all scintillators via programmable integration time
Positive and negative operating voltage and different PMT pinouts.
Feature summary – SiPM-3000
Suitable for 500kcps on NaI(Tl) or faster scintillators
Suitable for many scintillators via programmable integration time
Very low-noise integrated SiPM voltage supply
Very low trigger threshold: <10keV with 2MeV energy range.
Feature summary – Common characteristics
Histogram: 4K×32; Loss-less two-bank mode with 2× 2K×32;
List mode, pulse shape capture
On the fly pulse shape discrimination
Built-in programmable gain stabilization performed by embedded ARM processor
USB interface; Serial interface on PCB; default 115200 baud
FPGA customization possible for application specific product
ARM C-code customization possible for application specific product
Power consumption is only 300mW (5V@60mA)
Popular FPGA firmware options
Loss-less dual bank list mode buffer with 2047 events per buffer.
100ms time slice operation with 20-deep buffer, events and 1k histogram per slice.
Popular software options
MCA-3000 Users Manual
V 3.2, June 2021
By
Michael Momayezi
Phone 512-553-9933
Fax
512-553-9934
momayezi
email
@bridgeportinstruments.com
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Summary of Contents for Bridgeport MCA-3000
- Page 1 This document describes how to use the MCA-3000 from the graphical user interface and from Python scripts. Using the MCA Data Server, developers will find they can program the MCA-3000 in any language they want.
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Page 2: Table Of Contents
0x0103 (PMT-3000) or 0x203 (SiPM-3000). 2. Getting Started Open the Windows Device Manager and 3. Energy Spectrum connect the MCA-3000 to a USB port. Wait 4. Calibration until it appears in the Device Manager as an unknown device of type armMorpho or 5. -
Page 3: Energy Spectrum
count rate data and begin a new acquisition. height peak. Access the operating voltage The panel does not automatically refresh, so control by opening the display. arm_ctrl click the "Refresh" button to get an updated Enter a new operating voltage in the cal_ov energy spectrum. -
Page 4: Calibration
120MHz. event. For NaI(Tl) between 5°C and 65°C the MCA-3000 recommends a fixed hold off time For proper operation, the amplifier output for NaI of 1.2µs. The resulting throughput is voltage must fall within the 1.0V input range of shown in the next figure. - Page 5 After adjusting the high voltage to set the You can manually calibrate the detector, in maximum measurable energy, the user can now which case you have more freedom on how to vary the digital gain to map the entire energy do it.
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Page 6: Gain Stabilization
5. Gain Stabilization But the hold-off time has to be varied. NaI(Tl) pulses become very long when the All MCA-3000 offer gain stabilization that crystal temperature falls below 0°C. keeps the gain, the trigger threshold and the Consequently, the hold-off time has to be maximum measurable energy constant. - Page 7 detector should be packaged with good thermal 0 ⇒ Off; Use when calibrating a detector. insulation to achieve thermal time constants of 7 ⇒ Suspend; Keep all parameters as they 2 hours or more – to ensure that all components are.
- Page 8 It is field on the display. cal_target arm_ctrl implemented for all MCA-3000. The units ship Don't run the LED too fast. Keep in mind with LUT determined for NaI(Tl) at an that the LED pulses also cause a load on the integration time of 1.25µs...
- Page 9 5.8 Detectors and LED LED in the MCA not the detector: The PMT- 3000 can be equipped with an LED for the purpose of gain stabilization. The LED is mounted on the underside of the high voltage unit. The LED shines its light through the back of the PMT.
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Page 10: Summation Weights
All ADC samples are weighed the upper half. For both types of events there is equally. But the MCA-3000 offers a more fine- a separate event counter to measure count rates. tuned control: ∑... - Page 11 Factory default: The factory default for the weights is 32767, which is very nearly the same as 1.0. When psd_on=0, the weights are used for regular energy measurements, and having all weights to be equal and near 1.0, is a reasonable default.
- Page 12 Below we show the performance of such a PSD Weight uint16_t value PVT/NaI phoswich detector. 32768, 0x8000 Even small pulse shape differences can be used. The phoswich was constructed using a -0.5 49152, 0xC000 50mm×50mm NaI(Tl) crystal and a 3mm -0.25 57344, 0xE000 plastic scintillator (PVT).
- Page 13 In this example, we find that on the dividing line, , hence we select in order to map the dividing line to 0. In the MCA-3000 the pulse integral is approximated by sums over ADC samples. For a 40MHz ADC, 0.50µs means 20 ADC samples. ∑ ∑...
- Page 14 values (from the NaI) are significantly bigger than the blue β-pulse values, we apply a positive weight. The value of the positive weights is adjusted such that all βs map to <0 in the PSD histogram, and all γs map to >0 in the PSD histogram.
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Page 15: Analog
data acquisition board with a structure as Item Performance shown in the figure below. Sr-90 If detected, 95% are classified correctly. <0.005% false betas; with Cs-137 above the Cs-137 NaI top side. Background ~0.2cps β Max γ-energy: 3.2MeV; trigger threshold at Settings 50keV. - Page 16 On the USB bus devices are recognized by onto the device is shortened to 8 hexadecimal their Vendor ID (VID), Product ID (PID) and characters. Serial Number (SN). The vendor ID for Bridgeport Instruments is 0x1FA4. The Product © Bridgeport Instruments, LLC, 2021-03-11 bpi_mca3k_um_v3p1.pdf ...
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