Skip to main content

Photomultiplier Tube History and the Bell Laboratories Record

In our experimental search for H-Rays, we're using a NaI crystal attached to a photomultiplier tube, (PMT),  to detect the predicted x-ray radiation.  While studying up on photomultiplier tubes[1] this week, I came across quite a few interesting historical points.  Among these are:
1.  PMTs were first invented for use in movie theatre projectors to provide the sound tracks.
2.  Equipotential lines were important for design, but computers for the necessary didn't exist yet.  The lines were mapped by stretching thin rubber sheets over wood block models of the electrodes and rolling small balls along the sheets to predict how electrons would move between dynodes in the actual tube.[2]  The picture, (picture 1), below shows one of the models being used


3  PMTs were used as radar jammers in world war II.  When fully illuminated,they produce a very natural white noise that can't be distinguished from natural radio static.  The noise was amplified and broadcast to swamp enemy radar.

The article mentioned above is contained in the Bell Laboratories Record. If you're ever looking for an issue, or just want to do some old time tech reading, I found a repository of the back issues[3].

In addition to writing about PMTs, Pierce also wrote an interesting piece on the large balloon satellites that were used for microwave communications testing.  It included a rather spectacular picture of one of the balloons.


G+er's, +Jonah Miller and +Patrick D. Garvey pointed out that the satellites were instrumental in radio astronomy and the discovery of cosmic background radiation.[4]  One of the great things about writing about science on G+ is the incredible audience that frequently adds more information and interesting perspectives!





References:
1.  The Photomultiplier Tube Handbook
http://psec.uchicago.edu/links/Photomultiplier_Handbook.pdf

2.  The article on equipotential analog computers
http://www.americanradiohistory.com/Archive-Bell-Laboratories-Record/30s/Bell-Laboratories-Record-1938-05.pdf

3.  Bell Laboratory Record
http://www.americanradiohistory.com/Bell_Laboratories_Record_Issue_Key.htm

4.  Post with cosmic background comments
https://plus.google.com/108242372478733707643/posts/XTeaDbTNKaP


Comments

Popular posts from this blog

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1.  While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero.  This is typically explained in the following way.  While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare.  That doesn't stop us from looking for them though! Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2].  Cabrera was utilizing a loop type of magnetic monopole detector.  Its operation is in...

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

Now available as a Kindle ebook for 99 cents ! Get a spiffy ebook, and fund more physics The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems , there seem to be fewer explanations of the procedure for deriving the conversion, so here goes! What do we actually want? To convert the Cartesian nabla to the nabla for another coordinate system, say… cylindrical coordinates. What we’ll need: 1. The Cartesian Nabla: 2. A set of equations relating the Cartesian coordinates to cylindrical coordinates: 3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system: How to do it: Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables. The chain ...

More Cowbell! Record Production using Google Forms and Charts

First, the what : This article shows how to embed a new Google Form into any web page. To demonstrate ths, a chart and form that allow blog readers to control the recording levels of each instrument in Blue Oyster Cult's "(Don't Fear) The Reaper" is used. HTML code from the Google version of the form included on this page is shown and the parts that need to be modified are highlighted. Next, the why : Google recently released an e-mail form feature that allows users of Google Documents to create an e-mail a form that automatically places each user's input into an associated spreadsheet. As it turns out, with a little bit of work, the forms that are created by Google Docs can be embedded into any web page. Now, The Goods: Click on the instrument you want turned up, click the submit button and then refresh the page. Through the magic of Google Forms as soon as you click on submit and refresh this web page, the data chart will update immediately. Turn up the:...