We prepared a short note on how to build a dynode voltage divider network for inexpensive surplus XP2422/SN photomultiplier tubes. The XP2422/SN PMT is especially suited for gamma-ray spectral analysis when coupled to a NaI(Tl) scintillation crystal because of its high pulse-height resolution (PHR). The XP2422/SN is available from Sphere Research in Canada.
We recently learned the sad news that Dr. Akira Tonomura – a truly great experimentalist – passed away on May 2, 2012 during the course of treatment on pancreatic cancer.
We have been great admirers of Dr. Tonomura. Our blog’s banner is a cartoon representation of an experimental setup developed by Dr. Tonomura, through which in 1986 he showed single-electron buildups of electron wave interference fringe patterns. This experiment clearly revealed the dual nature of electrons and was described by Physics World magazine as the world’s most beautiful physics experiment, ranking above the historical experiments of Galileo Galilei and Robert Millikan.
The nice guys at the Yahoo GammaSpectrometry Group developed multichannel analyzer software for the $79 SainSmart DSO201 Pocket-Sized Digital Oscilloscope. The upload of the MCA software to the oscilloscope is really easy (via USB), and it allows the PMT probe shown in the book’s Figure 30 to be connected directly to the oscilloscope’s input with no need for a PMT amplifier!
Scionix in The Netherlands has taken advantage of the recent development of miniature mesh-type dynode photomultiplier tubes to construct small-diameter scintillation probes. Scionix’s miniature probes incorporate one of those PMTs, a NaI(Tl) scintillation crystal, and a built-in dynode voltage divider. Connection to the probe is made through a miniature high-voltage locking coaxial connector. Finding a mating connector is the main problem faced by enthusiasts who find these probes in the surplus market. Continue reading
Figure 34 in the book shows the schematic diagram for our photomultiplier tube (PMT) signal processing circuit has an analog output that is suitable for use with a sound-card-based multichannel pulse-height analyzer (MCA). However, if you already have a commercial scintillation processor that you would like to use with PRA, then you will somehow need to extend the typically narrow output pulses (e.g. 1 to 10 microseconds) so that they can be acquired through the sound card. Continue reading
An amateur-use open-source gamma spectrum analyzer is being developed by members of the GeigerCounterEnthusiast (GCE) Yahoo Group. This multichannel analyzer (MCA) is based on the STM32F103VBT6 microcontroller. It displays spectra on a color LCD.
To access the design files (and hopefully to participate in the development) you will need to join the GammaSpectrometry Yahoo Group (free membership). Join through: http://groups.yahoo.com/ Continue reading
In Chapter 5 of the book we list a short Matlab® program to integrate successive video frames from our diy intensified camera to image double-slit interference patterns obtained by shooting a single photon at a time.
The program listed in the book uses Vision for Matlab (VFM). However, this utility is not compatible with all versions of Windows and Matlab. An alternative is VCAPG2 by Kazuyuki Kobayashi available at http://www.ikko.k.hosei.ac.jp/~matlab/matkatuyo/vcapg2.htm (Also available from our SOFTWARE page). Continue reading
Figure 34 in the book shows the schematic diagram for the photomultiplier tube (PMT) signal processing circuit that amplifies the narrow pulses detected by the PMT probe. The discriminator stage removes small pulses produced by thermal noise in the tube. A pulse stretcher outputs pulses that can be heard on a speaker. In addition, the analog output is suitable for use with a sound-card-based multichannel pulse-height analyzer (MCA). Continue reading
The book’s Figure 32 shows the schematic diagram for a low-cost, variable-voltage PMT power supply based on a BXA-12579 inverter module that is originally designed as a power supply for cold-cathode fluorescent lamps. This under-$20 module produces 1,500VAC at around 30kHz from a 12VDC input.
We are posting this picture to help you build your own power supply. It shows the BXA-12579 that has been modified as described in the book. The op-amp to the right of the CCFL module is used to control the voltage supplied to the module. The high-voltage AC output of the inverter is rectified and doubled and filtered by the diodes and capacitors at the left of the CCFL module. Continue reading
This is the datasheet for the RCA 6655A PMT used in the probe shown in the book’s Figure 30: RCA_6655A_Datasheet
This is the datasheet for Hamamatsu’s replacement of the RCA 6655A PMT: Hamamatsu replacement for RCA 6655A R2154-02
Schematic diagrams for the probe are in Figure 29.
We are posting this picture to help you construct the variable-output, low-ripple, high-stability, high-voltage power supply described in pages 38-40 of “Exploring Quantum Physics Through Hands-On Projects.” The schematic diagrams for this power supply are in the book’s Figure 31. Output voltage (up to 2 kV) and current (up to 1 mA) are monitored via two LCD panel meters. Continue reading
Spectrum Techniques of Oak Ridge, TN – a top supplier of Exempt Quantity radioisotope sources and nuclear measurement instrumentation – released today our tutorial:
“Experiment Note: Exploring Compton Scattering Using the Spectrum Techniques Universal Computer Spectrometer” Continue reading
This is the surplus Gen III image intensifier tube (an MX-10160 Gen III intensifier tube used in the helmet-mounted AN/AVS-6 “ANVIS” aviation night vision imaging system, which we purchased on eBay®) that we used to build our setup to image interference patterns from our single-photon two-slit setup (book‘s Figure 93). The tube is supplied by 3VDC from two AA cells. We used the same camera to record interference patterns from a single-photon Mach-Zehnder interferometry setup (book‘s Figure 132). Continue reading
