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On the left are my monster scintillator crystals. The two 2" diameter x 14" long crystals are absolutely clear. The 1 1/2" x 8" is so-so. The 1" x 8" is very green and opaque.
The small scintillator crystals on the right are perfect to replace dead crystals on the Precision Radiation Instruments (PRI) 111-B. Even the most opaque one (lower right) is good enough for amateur use (below). A refurbished 111-B is shown measuring 10uCi Cs137 at 1ft. |
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I wish I had the chance to develop pacemakers in the days they were powered by nuclear batteries… I took these pictures of a Medtronic nuclear pacemaker and of a plutonium 238 pacemaker “battery” on a recent trip. One of my friends keeps some of these rare specimens in his private collection. The “battery” is actually a vacuum flask (a “Thermos”) with a Pu-238 pellet in its inside. The decay of the Pu-238 releases heat which keeps the temperature of bimetallic contacts high in reference to the temperature of their coupled metallic pairs on the outside of the flask (37 degrees C). A parallel-series arrangement of the thermopiles generates enough current to drive a pacemaker circuit. The “battery” is hermetically sealed within an enclosure that can withstand direct impact by a high-caliber bullet without rupture of the plutonium core. Click here for THE article on nuclear pacemaker batteries [.pdf]: Fred N. Huffman, et al., RADIOISOTOPE POWERED CARDIAC PACEMAKERS, Cardiovasc Dis., 1(1): 52–60, 1974. (Copyright notice: This article is free from www.pubmedcentral.nih.gov). |
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Implantable atomic “batteries” (in my dreams…) |
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Radiation |
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D. Prutchi, J.L. Prince and L.J. Stotts, “X- and Gamma-Ray Hardness of Floating-Gate EEPROM Technology as Applied to Implantable Medical Devices”, IEEE Transactions on Electronic Components and Packaging Technology, 22(3), 390-398, 1999.
There is a growing need for the inclusion of nonvolatile memory within implantable medical devices in order to store product identification, operating parameters, calibration information, as well as patient and diagnostic data. Due to the critical nature of the application however, the data retention reliability is of utmost importance. In the case of nonvolatile memories, a source of concern regards their exposure to ionizing radiation as the result of diagnostic or therapeutic procedures performed on the patient. This paper reports on X- and gamma-ray experiments and calculations on a representative implantable-grade ICs to 150 kVp X-rays up to the maximum achievable 27 rad(Si)/s for a total dose of 200 rad(Si). Unbiased parts had no failure to an average total-dose of 40.9 krad(Si). Parts were also characterized with respect to exposiure to Co60 gamma-rays. Data were analyzed in comparison to maximum therapeutic photon radiation doses. The importance of this information is rapidly increasing as the effects of medical diagnostic and therapeutic radiation are becoming an issue of concern to physicians who often encounter the need for radiotherapy in the growing population of patients implanted with pacemakers, defibrillators, neural stimulators, and drug-delivery pumps. As such, results from future tests under the specified reporting methods should enable the development of concise guidelines to aid physicians in effectively managing patients with active implantable medical devices. |
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Rad-Hard Integrated Circuits for Implantable Devices |
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X-Ray Sources |
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For detailed technical information on the PRI 111B, as well as great scintillator-based projects (e.g. finding dinosaur fossils with a scintillator) see Charlie Thompson’s website. |
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Scintillators |
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Some x-ray tubes include a cold-cathode tube (top), a “podiatry” type tube that has a focal spot of ~2mm and can be driven with up to 100kV @ 10mA (center), and three old 6BK4 TV rectifier tubes (bottom) that can be driven to generate x-rays when following the instructions presented in the Bell Jar.
If you are interested in this sort of projects, I recommend that you buy the compendium CD ROM of Scientific American's "The Amateur Scientist". In addition, C. L. Stong’s “Scientific American Book of Projects for the Amateur Scientist” has a chapter describing Harry Simons’ impressive experiments using antique 01 tubes driven by a homebuilt Oudin coil.
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Safety First! |
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It is smart to energize electron tubes inside a lead-shielded box (left picture). It is possible to peek through the lead-loaded window. I keep close tabs on any exposure (picture on right) using a Russian-built Geiger totalizer (upper left), a “Civil Defense” V-700 model 6-b survey meter retrofitted with a military-style Geiger probe, and the two dosimeters that I use at work when attending device implants (top right): a Rados RAD-60R CZT unit and a Luxel badge. CLICK HERE for cool mods to the CD V-700! |
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▲ This is a radiograph of a RADOS dosimeter directly exposing black and white Polaroid film. The black circle on the bottom left is the Cadmium-Zinc-Telluride (CZT) Detector. CLICK HERE for more radiographing with Polaroid |
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One of my main interests is the analysis of natural-occurring background radiation. The picture on the left shows a 14” long x 2” diameter NaI scintillator coupled to a high-gain photomultiplier tube. The picture on the left shows a scintillator/PMT assembly together with my home-made pulse shaping amplifier. I run spectral analysis of my data using a home-made, PC-based multichannel pulse-height analyzer (MCA). |
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Particle Accelerators and Electron Microscopes |
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▲ This is my vacuum bench. The main pump is a 2-stage Leybold Trivac. High-vacuum is achieved using an oil diffusion pump (under the bench). Higher vacuum is reached using a micromaze pump. I have 2 thermocouple and 2 ion gauges. I can evacuate down to ~10-8 Torr. My main power supplies are 2 Van deGraaf generators in tandem configuration (one positive and one negative to reach ~1,000,000V in a dry winter day) and a 300kV oil-immersed multiplier.
Shown here on the vacuum setup is a simple electron microscope that I built, also based on an old Amateur Scientist column. I cut the screen of an old oscilloscope CRT to use it as the display screen. The electron gun is cold-cathode.
If you are interested in building a similar setup, I strongly recommend the following books: |
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© 2005 David Prutchi. All rights reserved. |
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CLICK HERE for instructions on how to add chirping to the Master-1 Russian Geiger Counter |
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◄ This nuclear pacemaker was manufactured by my good friend Dr. Orestes Fiandra in Uruguay. It was powered by a McDonell-Douglas Betacel 400 which had promethium-147 sandwiched between semiconductor wafers. As the radioactive promethium isotope decays, it emits β-particles (electrons). The impact of the β-particles on a p-n junction causes a forward bias in the semiconductor similar to what happens in a photovoltaic cell (a solar cell). PAPER IN SPANISH [.pdf] |
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◄ How much radiation do you receive when you fly in a commercial jetliner? I often take my MASTER-1 Geiger counter along on trips and take measurements as we fly. CLICK HERE FOR GRAPHS |
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I don’t want to compromise the security of our country. If you are a government agent (FBI, CIA, DEA, FDA, FAA, etc.) and find material in these pages that you find objectionable, please contact me so that I can rectify the situation. |
