Thursday, October 23, 2014

Pickup Coils, Faraday's Law and Back in the Lab! Lab Book 2014_10_23

 As always, look to the bottom of the post for background on what's going on.

Finally, enough of theory and presentations!  I got back to the lab today!  Here’s the apparatus I built/used.

NOTE:   As always, look to the bottom of the post for background on what's going on.




No, the oscilloscope is not sticking its tongue out, that’s a floppy disc.  Remember those?  

The small solenoid is what’s deemed a pickup coil. 


It’s the first prototype, of the coil that will be used to measure the actual currents and magnetic fields produced by the can crusher magnet.  It’s exactly what it looks like, six complete turns made from a jumper wire.  The Styrofoam cup is to avoid abusing the small magnet block too much when it’s dropped.  

The ‘scope pictured can capture a single waveform.  Here, it’s slowed way down to make a sweep over the course of several seconds.  It’s being used to look at the signal from the coil as the magnet is dropped through it.  Each set of spikes you see is created by dropping the boxy looking magnet through the solenoid.  Faraday’s law does the rest.


This is a very basic test run in preparation for measuring the changing magnetic field that will be generated by the pulsed magnetic field that’s to be used in the experiment.  Here’s a trace of a single magnet drop



Coil diameter  13.5 1/16ths
Number of turns 6
3178



Background
Hirsch's theory of hole superconductivity proposes a new BCS-compatible model of Cooper pair formation when superconducting materials phase transition from their normal to their superconducting state[1].  One of the experimentally verifiable predictions of his theory is that when a superconductor rapidly transitions, (quenches), back to its normal state, it will emit x-rays, (colloquially referred to here as H-rays because it's Hirsch's theory).

A superconductor can be rapidly transitioned back to its normal state by placing it in a strong magnetic field.  My experiment will look for H-rays emitted by both a Pb and a YBCO superconductor when it is quenched by a strong magnetic field.
This series of articles chronicles both the experimental lab work and the theory work that’s going into completing the experiment.

The lab book entries in this series detail the preparation and execution of this experiment… mostly.  I also have a few theory projects involving special relativity and quantum field theory.  Occasionally, they appear in these pages.

Call for Input
If you have any ideas, questions, or comments, they're very welcome!

References
1.  Hirsch, J. E., “Pair production and ionizing radiation from superconductors”, http://arxiv.org/abs/cond-mat/0508529

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