Copasetic Flow

Alternate Title:  How Could Something So Pretty be So Broken? Summary It finally became too cumbersome to work with the can crusher simulation code in script form.  the bulk of this morning was spent in meetings and reworking the can crusher code to be object oriented.  The object oriented refactoring was completed and tested and works great!  It’s now very easy to run multiple simulations and compare their results.  The next step is to write code that runs the simulation to the peak current point and then plots the magnet field in on a spherical surface that will correspond to the surface of the superconductor Pb sample being used.  There are other simulations that need to be done as well.  For example, finding out how the current traces change when the temperature of the material is 4.2 K, the temperature of liquid helium. The leak detector problem has been isolated.  The Pirani gauge that measures the vacuum on the diffusion pu...

Summary: The leak detector stopped working correctly several weeks ago.  It didn't exactly depart his mortal coil so much as just stop being useful.  Sort of like a major league baseball catcher hunkered in a hockey goal.  It looks sort of like it has the right equipment, but it obviously incapable of performing it's tasks in any sort of meaningful way.  It boils down to this, the mechanical roughing pump is still pulling a vacuum that should enable the diffusion pump, responsible for doing the detailed vacuum work, to switch on, and yet the diffusion pump abjectly refuses. If you're new to the experiment, the background of what's going on here in broad strokes can be found at the bottom of the post. Lab Book 2014_07_25     Hamilton Carter Leak Detector Work Leak detector testing was resumed.  The first test was to check the vacuum on the end of the vacuum hose coming from the roughing pump and normally attached to the diffusio...

Posts will be a bit terse and scattered for the next few days.  Today I was looking into Hirsch's answer to the question "How'd you get all that excess charge got up onto the surface of that superconductor anyways Hoss?", (appropriate nod to Ray Stevens and Shriners everywhere here).  Super, super, super attentive readers might remember that the upcoming h-rays experiment [7] will be looking for Bremsstrahlung radiation produced by this theoretical excess surface charge density when the superconductor quenches. What I found through the referenced series of Hirsch  articles[1][2][3][4] relates to the effective mass of electrons I spoke about yesterday [6].  Hirsch makes the inference that since the mass of the electrons measured within superconductors corresponds exactly to the rest mass of the electron, then they must not be interacting with either the lattice ions of the superconductor, or the other electrons in the superconductor.  Hence, he ...

After yesterday's attenuation calculations, I'm trying to find out if I can place the scintillator directly into the liquid helium Dewar to avoid the attenuation of flux due to the Dewar walls and solenoid windings.  I came across an interesting article that was a portion of Fernand Bedard's PhD dissertation in 1956.  It's interesting for lots of reasons.  First, Bedard was working with Hans Meissner.  Second the article mentions currents across insulating junctions with superconductors on either side in 1956, several years before Josephson would do his Nobel prize winning work on Josephson junctions.  Finally, Dr. Bedard wound up working for the NSA! Then, there's the pragmatic stuff.  It looks like they did place their NaI crystal in the Dewar.  The article also mentions that they were able to load 2 liters of liquid helium using only 5.5 liters.  They apparently lost only 3.5 liters to boil off!  The article also has an excelle...

I received detailed plans for the liquid helium Dewar that's going to be used in the h-ray experiment yesterday and spent some time calculating the amount of attenuation we can expect to the x-rays theoretically produced by our quenched Pb superconductor.  I'm making the assumption that most of the attenuation of x-ray flux will come from the aluminum walls and aluminum backed insulation, not from the plastic walls.  A cross-section of the walls is shown to the left, (picture 1).  The wall on the left of the cross-section is made of .125 inch thick aluminum.  The five sheets of insulation between the inner and outer walls are Mylar coated with .003 inch thick aluminum.The inner wall on the right hand side of the cross section is constructed of .1 inch of 'low thermal conductivity plastic'.  This gives me a grand total of 0.35 cm of aluminum between the source and the   detector.  The graph shown below...

This is just a series of rather scattered notes on things that I need to keep in mind for the h-ray experiment as well as things that are going on in class this week and how they're not that disconnected. Shubnikov, who I've mentioned before [1], (picture 1), in reference to the intermediate state of superconductors, came up in quantum mechanics class this week.  The topic of discussion was Shubnikov-DeHaas oscillations.  These are oscillations of the resistance of a material with respect to the strength of the magnetic filed it is exposed to.  It occurred to me the the graphs of the oscillating resistance[2], (picture 2 below), looked a bit like magnetron operation because at low magnetic fields nothing much happened due to the field being too low to bend the electrons into a complete orbit. A little more searching and reading revealed I wasn't necessarily the only person who ever thought so.  I ca...

I took the first look at the cryostat that is probably going to use for the hole theory of superconductivity experiment.  A cryostat is a vessel for holding a coolant or cooling system, (in our case, liquid helium), and the equipment/samples for an experiment.  Because helium transitions from a liquid to a gas at just over four degrees Kelvin, the cryostat has two walls separated by a vacuum space to insulate the liquid helium inside from the room level temperatures outside, just like a thermos. Before I get to much further into the details of the cryostat, I'd like to coin a phrase.  As those of you who already read the proposal for the experiment[1] know, Dr. Hirsch of UCSD has proposed a new model for superconductivity[2], and one of the predictions made by that model is that superconductors will emit Bremsstrahlung radiation[3] when they are quenched back into their normal non-superconducting state.  It's getting to be a bit much to type Bremsstrahlung a...

I've been looking lately at using an already constructed superconducting magnet instead of building my own for the upcoming experiment, (an Experimental Search for the Bremsstrahlung Radiation Predicted by the Hole Theory of Superconductivity )[1].  The issue at hand is that the bore isn't large enough to accept the originally planned 3.8 cm radius spherical Pb sample.  I took a look this morning at what reducing the sample size would do to the energy of the predicted radiation in electron volts as well as what the dependency of the radiation flux would be with respect to sample size.  The two formula for the energy and the flux (pictures 1 and 2) are: See the aforementioned proposal as well as reference 2 for more details. Plotting each of these versus R, the radius of the sample gave the following plots, (pictures 3 and 4).  If the radius is reduced all the way down to 2 cm, the fall off in energy isn't unacceptable.  It still lands in the...

A quick review of what I'll be looking at over the course of the upcoming week.  This is as much to get my own thoughts in order as anything else. Quantum Mechanics: I'll be working on still more uncertainty and harmonic oscillator problems in QM this week.  What a surprise right :)  Specifically, this week, I'll be calculating matrix elements for both position and momentum squared using both the Hermite polynomial recursion operators and the ladder operators.  These are covered in chapters 5 and 10 in Merzbacher.  I was playing around with one of the recursion relations (picture 1)  for Hermitian polynomials earlier in the year and wound up with the following kind of interesting table.  You can see the n level of the wave function moved out of the way by the successive application of the recursion formula which amounts to the successive application of the x operator, or a sum of the raising and lowering operators (picture 2). I...

I've been following a literature search for the last few days that's led to a very interesting point.  Superconducting tin has different quench points, (via magnetic field), depending on the orientation of the direction of current flow in the sample and the direction of the applied external magnetic field[ 1 ].  My next job will be to determine if Pb has the same qualities, and if so what that means for the experiment. Pb was chosen as the sample for our experiment because of the relatively low magnetic field strengths at which it can be quenched.  It was mentioned by Hirsch in one of his articles predicting Bremsstrahlung radiation from quenched superconductors that the super conductor should be quenched 'quickly'.  It's unclear at the moment what effect this squirmy quality of supercurrents vs. magnetic field orientation will have. Flow of the Literature Search: And now, just a few notes on how I arrived at the Shubnikov article.  Hirsch who originat...

First, the really great news!  My research proposal won first place at the Texas Academy of Sciences meeting on Friday!  That means I've got the money to purchase liquid helium and play with a superconductor this summer.  The proposal can be viewed below on the blog, or you can grab it from [1] if you're reading this somewhere else. Now, the question.  I've been reading lots of posts from G+ers like  +Mark Hahnel ,  +Laura Wheeler , and  +Emily Coren  on the value of open access and communicating science to the public.  I'm thinking of doing something cool like Google+er  +Katrina Badiola  has done with her lab notebooks.  I'm curious how this works out and what experience people have had with it.  If you can answer any of the following questions, that would be awesome!  If you'd like to answer anonymously, leave and anonymous comment on the blog post. What do you think the benefits of an entirely...