The Portable Universal Radiation Spectrum Analyzer.

SHV Connector.

Click here for Example Data:

Front view, battery compartment removed.

Rear view.


Page under construction:  Please check back often as new items are constantly being added.

Update: Click here to view screen shots of the new program 

Update: Faster RS-232 with a maximum of 460,800 Baud Click for details

Update: Super Low Noise test results. Low end Spectrum Expansion!  Click for details

Update: Spectrum Shift test result indicate doing better than units triple the price! Click for details

Update: Hardware counter tests show this new CPU can indeed count in excess of 30 (thirty) million counts per minute. Click for details.

Update: Optional Extra memory board expands autonomous operation enabling 48 full 32 bit spectra to be stored. Click for details.

Some Key Features:

The New version of this Portable Universal Radiation Spectrum Analyzer has many advanced features based upon the experience I gained from the original design. The signal to noise ratio is significantly higher and therefore reduces count time as well as allowing a better low end range, high end range is of course as good as ever.

The lower noise allows much higher gains to be used. The microcontroller speed has been increased by 55%, this  reduces dead time and the overall counting times are far shorter than that of the older design. A one micro-curie Cs-137 source can produce a fully quantifiable spectrum in less than two seconds!

This high speed response makes it ideal for portal and site monitoring.

In addition, the lower noise level allows the detection of peaks at the very low end of the spectrum.

The original unit came in a small handy box, I decided to retain the original size, and add many new features by using more modern miniature components.

My original URSA(tm) (tm registered to Paul Steinmeyer of RSA Inc.)  used AC, DC, or battery power and could operate to full specification for about 30 Hours from one set of alkaline batteries. In this new design I decided to incorporate a battery of NiMH cells, and provide a built in, fully automatic charger. My new design runs for about 22 hours from a fully charged set of NiMH batteries, that gives the user two full 8+ hour days of use without the need to recharge. Of course NiMH can be "topped up" at any time and do not exhibit the chemical memory problems associated with Nickel Cadmium cells. The unit will fast charge automatically with full temperature, slope, and time monitoring of the charging process. If the cells are too cold, Fast Charge will be held back until the cells reach room temperature; this ensures reliable and fully automatic charging for the NiMH cells. With such an excellent battery life I decided not to bother with allowing the use of alkaline cells, it simply is not needed.

The front panel has two connectors, one BNC and the other a high voltage connector SHVC or "C type" . The "two connector feature" is a migration from the old version which was known as type SC. However the old SC version was a retrofit which is not the case in this new design. The purpose is to allow almost any type detector to be used. External Power +12Volts is made available on the front panel connector, with enough power to run fine detectors such as the Spear CZT.

A major new feature is the ability to store 24 full spectra in memory allowing the unit to operate autonomously, and does not need to be connected to a PC. The old design had a modem feature and that feature has further been improved upon in this new design..

By simply adding a good Hayes compatible modem it is now possible to do remote site monitoring with the only requirements being the access to power (solar is OK) and a phone line ( I'm working on a cell phone interface). The Portable Universal Radiation Spectrum Analyzer can be fully controlled, and operated by a modem connection. It can also be setup to run autonomously and store a total of 16  spectra for 24 hours (48 spectra with optional memory card). Each spectrum  has a full BIN count of 4096 values, each BIN stores a 32 bit value, allowing a maximum count value 4,294,967,295 for each BIN. Of course with a direct PC connection the number of spectra that can be saved is virtually limitless.

Spectra are stored in 256K BYTES of NON Volatile memory (does NOT require battery backup). This is NOT using EEPROM(flash) which has a limitation in the number of times a location can be written to and would not be reliable for this application. The memory used has a guaranteed ability to read and write any location up to 10 BILLION times before a memory location becomes impaired, while EEPROM(flash) has a typical 1 million writes (unlimited reads) per location before memory is impaired.

In the case of remote site monitoring. The Portable Universal Radiation Spectrum Analyzer can be called up and all 21 spectra can be transferred in one session.

Currently under development is a new feature which will allow the The Portable Universal Radiation Spectrum Analyzer to be configured to monitor several ROI's and if any exceed the count threshold of CPM the unit will dial up a phone number a to report a warning, or drive any external device directly. On calling the preset number it will attempt to connect (by modem) to a dedicated PC and upload the spectra and warning messages. 

The stationary version has the ability to connect to any FTP server, and transfer the stored spectra as well as issue warning in a fully unattended mode. The stationary version is currently under development and should be ready some time this fall. More details about this version later !

Hardware Specification:

Excellent example of Eu-152 spectrum, and it only needed 90 seconds of counting time.

Using higher gain to expand the lower channels, this is made possible because of the excellent low noise figure the unit has. Typically when a higher gain is used the noise will swamp the signal and a much longer count time will be required to get a similar spectrum.


More Great spectrums:

Old Data

Lantern mantle. Count time 900 Seconds.

Old Data. 

Sandstone from Utah. Count time 900 Seconds.

Am241.jpg (19787 bytes)Old Data. Typical JAMCA response for Am-241. 


New Improved version. Outstanding response and low noise.  Notice the 13.9keV peak is visible. Also notice the clean spectrum from 1keV to 13.9keV..... 

Now for some FAST results

Notice the 32keV peak if well defined and not jammed against the left side of the spectrum. This is a direct result of the very low noise design.

Only 10 seconds counting time and a beautiful Cs-137 spectrum ! 

Only SIX (6) seconds and a full Cs-137 spectrum... ! it gets better....

Wow ! A clean Cs-137 spectrum in THREE (3) seconds... Hang on it gets even better...

In a situation where high speed computer identification of a spectrum is needed, the quality of this FAST ( 1.5 Seconds) spectrum would be ample to achieve that goal.

C type HV connector.

Speaker grill.


Super Low Noise Design: It is a known fact that NaI(Tl) Gamma Scintillators  have a problem resolving the low end of the spectrum, by studying other designs I concluded it was not only the detector that caused a problem at the low end of the spectrum, in fact many MCA's are so electrically noisy they tend to swamp the low end of the spectrum with system noise, and blame the poor resolution on the detector. With this in mind I designed The Portable Universal Radiation Spectrum Analyzer to have as little system noise as possible. The benefit can be seen in these two examples of the same spectrum.

Normal view.

The blue circle outlines an area of interest at the low end of the spectrum. As can be seen the 32 keV peak is well off of the left side of the spectrum, and there are data to the left of it.. With such low noise, it is now possible to apply an expansion factor to the low end of the spectrum and make use of it.

Low end expanded View.

In this expanded view, I underlined in green the area that contains data, and not just noise. This is the area many MCA's can't show you, and simply tell you that system noise blocks the data ! The Universal Radiation Spectrum Analyzer shows you as much data as a NaI(Tl) Gamma Scintillator can deliver, and not the system noise.... ! MCA's costing much more can't do this...  

You may notice a difference in these two spectrum images.... They are from the new program. Click here to view screen shots of the new program. 

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(C) Copyright 2005 Hans Wedemeyer, Houston, Texas, U.S.A. All Rights Reserved.