Search found 998 matches

by Rich Feldman
Tue Nov 13, 2018 6:57 pm
Forum: New User Chat Area
Topic: Crystal synthesis inside a vacuum?
Replies: 3
Views: 177

Re: Crystal synthesis inside a vacuum?

At the opposite extreme, tons of synthetic quartz crystals are grown at pressures up to 1500 bar (21,000 psi), from alkaline aqueous solutions at temperatures around 380 °C, mimicking the natural geological method. qtz4.jpg That's barely above critical temperature, but almost 7 times critical pressu...
by Rich Feldman
Thu Nov 01, 2018 1:57 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: BCS detectors for neutrons
Replies: 0
Views: 148

BCS detectors for neutrons

Some online reading, inspired by Kai's project, turned up reports of Boron Coated Straws. Anybody here seen or heard of them? The developers hope to profit in the homeland security market, among others, in this era of limited helium-3 supplies. bcs1.JPG Very briefly, we have: [*]Extra narrow proport...
by Rich Feldman
Mon Oct 29, 2018 5:51 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Neutron Detector and Moderator Test
Replies: 9
Views: 892

Re: Neutron Detector and Moderator Test

Nice work. Thanks for sharing. Is the black mark on the edge of your work surface (was going to say, your counter) a reference for putting detector in the same place each time? For people new to neutron physics, how about demonstrating some other geometries? Instead of surrounding the detector with ...
by Rich Feldman
Tue Oct 23, 2018 12:39 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: How to test the quality of heavy water (D2O)?
Replies: 7
Views: 946

Re: How to test the quality of heavy water (D2O)?

Oh what fun, infrared spectra of water! Here's an animated gif v1.gif from http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html, which lists wavenumbers for 12 isotopically different kinds of water. Here's another reference: https://analusis.edpsciences.org/articles/analusis/pdf/1999/06/hein...
by Rich Feldman
Mon Oct 22, 2018 4:51 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: How to test the quality of heavy water (D2O)?
Replies: 7
Views: 946

Re: How to test the quality of heavy water (D2O)?

Roberto, thank you for posting the infrared spectrum plot. A thing I hadn't seen before. Anybody know if gaseous D2, H2, HD mixtures can easily be assayed by absorbtion or emission spectra? Here's a warning for conventional density measurements, even with a picnometer. They say D2O is very hygroscop...
by Rich Feldman
Sat Oct 20, 2018 7:56 pm
Forum: FAQs: Vacuum Technology
Topic: #4 FAQ: vacuum gauges - pressure measurements
Replies: 6
Views: 12727

Re: #4 FAQ: vacuum gauges - pressure measurements

Oops, compelled to correct a rare mis-statement by John. One bar is exactly 10^5 pascals. Most meteorologists use millibars to measure, record, and forecast natural air pressure. The "standard" pressure at sea level is 1013.25 millibars. This month's devastating Hurricane Michael had surface pressur...
by Rich Feldman
Fri Oct 12, 2018 8:11 pm
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Frequency effect in the operation of a MOT.
Replies: 4
Views: 1161

Re: Frequency effect in the operation of a MOT.

Welcome, Cai. Nice work there, measuring the transformer with different resistive loads. Then reporting with a well-labeled chart (and excellent written English). Did you make sure the primary voltage was constant during your frequency sweeps? Have you tried making a circuit model of the transformer...
by Rich Feldman
Wed Oct 10, 2018 12:02 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: neutron chiller exhibit
Replies: 0
Views: 421

neutron chiller exhibit

Today I had the good fortune to visit NIST in Gaithersburg, MD, for a technical seminar. It would have taken a lot more advance planning, maybe even a letter of recommendation, to be allowed into NIST Center for Neutron Research. But there are some cool places open to badged but otherwise unescorted...
by Rich Feldman
Tue Oct 09, 2018 11:32 pm
Forum: Images du Jour
Topic: HEAS 2018 Event Photos - Comments
Replies: 11
Views: 787

Re: HEAS 2018 Event Photos - Comments

Here are a few more.
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Some folks did not go to dinner, but cooked out on Richard's front lawn.
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T.R. Leary's Bismuth crystals.
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T.Even back by the lab, out into the lawn, more goodies.
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A typical small discussion conclave, of which, there were many.
by Rich Feldman
Sun Oct 07, 2018 10:40 pm
Forum: Images du Jour
Topic: Bullitt 50th anniversary
Replies: 0
Views: 323

Bullitt 50th anniversary

Hey Richard, you showed us pictures of your fast cars. Now I can't find your phone number. bullitt.jpg . Tonight and on Tuesday, there are nationwide screenings of Bullitt movie on its 50th anniversary. 2pm and 7 pm, at least in Eastern time. Incl. Regal Virginia Center 20, a stone's throw from Texa...