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!
Gunnplexers are becoming scarce in the surplus market, but X-band motion detection is very much alive. X-band detection modules are available for OEM applications, and fortunatelly, Parallax has a unit based on this module available for $34.99.
diy Quantum Physics was featured in Make Magazine, Volume 31: Punk Science (page 76).
Today I found two Perkin Elmer SPCM-AQE-13-FC SPCMs for sale on eBay at $400 each. eBay auction numbers are 280877451350 and 280877453169. I am passing along this information in case that blog readers may be interested. I have no connection whatsoever to seller.
Image Credit: Images Scientific Corporation
Images Scientific Corporation just announced a new Geiger counter wand base provides a stable platform to hold the Geiger counter wand for experiments. The physical dimensions of the holder are 2″ wide by 12″ long. The length of the sled has markings in both metric and imperial.
The sled isotope holder provides a stable and moveable platform for radioactive isotopes 1″ diameter discs. The sled isotope holder is available in two sizes: One that holds 1/8″ thick discs and the other to hold 1/4″ thick discs.
When used in conjunction with the Sled isotope holder a number of nuclear experiments may be performed such as the Inverse Square Law of radiation, half life, shielding effects, etc.
Someone (I don’t know the seller) is selling brand new Perkin Elmer C30902E Silicon Avalanche Photodiodes on eBay. Auction number: 200747161278.
These are NOT chilled by a thermoelectric cooler, so their internal noise may be too large for experiments with entangled photons unless you rig some sort of external Peltier element to keep them chilled. However, if you are developing a SPCM, using $91 SPADs during debugging is a lot better than frying $1,000 TE-cooled SPADs.
The book’s Figures 70 and 71 show our d.i.y. version of a popular apparatus to measure alpha particle scattering. The figure above shows additional views to help you build your own. The apparatus allows you to demonstrate alpha particle scattering discovered by Ernest Rutherford in 1908. Fundamental to the discovery of the atom’s structure, the experiment demonstrates that the charge of the atomic nucleus is concentrated at the center of the atom. Continue reading
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
Many surplus scintillation probes have a single connector through which the PMT is fed with high voltage and the anode signal is output. However, this may require an external “Bias-T” (a high voltage / signal splitter) to connect the probe to a high-voltage power supply that is separate from the PMT amplifier/processor. 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
Experimental chemistry is not our forte, so we prefer to use professionally-manufactured quantum dots for the Schrödinger’s Wave Equation experiments we discuss in the book‘s Chapter 7. However, if you are interested in synthesizing your own quantum-dot nanoparticle suspensions, we recommend that you take a look at the detailed instructions prepared by Professor George Lisensky at Beloit College for the Preparation of Cadmium Selenide Quantum Dot Nanoparticles (Local printer-friendly copy at: CdSe_Quantum_Dot_Synthesis). Continue reading
Our two prior posts show how to build very high voltage power supplies using flybacks from old color TVs. The advantage of the method we use is that any flyback can be driven, regardless of how its primary is wired. This is because we wind our own primary using litz wire. Continue reading
We use the flyback-driver circuit shown in our d.i.y. 250 kV DC power supply in many other of our setups, so we built a stand-alone universal resonant transformer driver. Continue reading
High voltage DC power supplies are used by science enthusiasts for powering electron tubes and x-ray tubes, charging high-voltage capacitors, powering electrostatic “levitators”, etc. Many of these power supplies use a flyback transformer to produce high voltage at high frequency (AC), followed by a “Cockroft-Walton Multiplier” to rectify and dramatically increase the voltage.
The Cockroft-Walton multiplier uses a cascaded series of diodes and capacitors to generate a high voltage DC potential from an AC input through a circuit topology that uses diodes to charge capacitors in parallel and discharge them in series. The output polarity of the Cockroft-Walton multiplier depends on the way in which its diodes are oriented, so the output polarity (referenced to ground) of a high-voltage DC power supply is usually set during the design.
However, since some of our physics experiments require one or the other polarity, we build our Cockroft-Walton multipliers with an extra capacitor so that we can make our HV power supplies output either positive or negative high voltage referenced to ground. Continue reading
Military DT-590A/PDR-56 “x-ray” probes are widely available in the surplus market. They were meant to be used with the military Radiac Set AN/PDR-56, which is a portable scintillation-type instrument used for detection of plutonium-239 contamination. In addition to emitting 5.1 MeV alpha particles, Plutonium-239 also emits gamma rays in the energy range of 14 to 21 keV. Because these gamma rays are more penetrating than the alpha particles, they travel further in matter and air and can be detected at longer distances from the ground. The probe uses a CaF2(Eu) scintillator/photomultiplier combination to detect these 14-21 keV gammas from Pu-239. The discriminator inside the probe is factory-tuned to detect only pulses from the Pu-239 gamma rays. Hopefully you don’t have plutonium contamination in your basement, so you can set the discriminator window wide open to make the probe sensitive to a much wider range of gamma energies. In addition, you can replace the CaF2(Eu) crystal by a NaI(Tl) scintillation crystal assembly. This will turn the instrument into a general-purpose gamma radiation detector that will outperform virtually any handheld Geiger counter in the detection of 100keV to 1.3MeV photons.
