Sunday, July 20, 2014

Cs 137 Spectrum at Last? Lab Book 2014_07_19

Summary:  I'm still checking and re-checking the NaI detector.  I've yet to get a reliable spectrum out of it, but last night's run at least has distinguishable peaks.  The company that made our detector 50 years ago believes that we probably do have an RCA 45xx series photomultiplier tube which would mean that the 2400 V bias I have to drive the tube at to get  a signal is actually OK.  The 45xx series has a maximum bias voltage of 2500 V.

If you're new to the experiment, scroll to the bottom for background.



The Cs137 spectra that was started at 3:13 PM yesterday was ended today at about 9:50 AM.  The photo of the spectrum follows


There are a number of oddly shaped peaks that may ben been created by channel overflow now that I think about it.  The data was printed and the linear chart is shown below:


If I ‘fix’ the supposed channel overflow by adding the value of the full register back in to the count, on the first step I get:

Which fixes the two peaks to the right, but not the one to the left.
Working under the assumption that the register overflowed twice in this region, I added in two full register counts to these data points and wound up with

We may be able to assume that the two non-plateau peaks are the two peaks associated with Cs 137.  I’m running a Co60 spectrum now and should have results by the end of the day.

Here’s a picture of the Cs137 sectrum again for reference.


Hunh, Cs137 only has one noticeable peak, or at lest one peak that should be larger than all the rest.  I've been told that our detector shouldn't be able to see the 32 keV line to the left of the graph.


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

Friday, July 18, 2014

Operation Smoke Puff, HAARP, Chemtrails, the Ionosphere, and Crowd Sourced Citizen Science

There's an ongoing effort to save HAARP from the demolition block[4], and as it inevitably does in all matters HAARP, the topic of chemtrails came up.  Chemtrails are by and large considered to be an urban legend, but like all good legends, it turns out there's more than a trace of truth embedded in the story  Perhaps the chemtrail legend has propagated so well because the ham radio community at large was involved in the first experiment that might have blossomed into the chemtrail mythos.  During a magical period, in the mid '50s  the United States Air Force experimented with augmenting the performance of the ionosphere, (think HAARP), by creating airborne clouds of particulate reflectors, (think chemtrails).

In his landmark 1958 article describing the experiment[1], author Michael Gladych, (expect to see  more about Gladych in these pages soon), first explained what the ionosphere was, first in words:

"In this electronic age, everybody knows that the ionosphere is an electrified upper atmosphere region that bounces off radio waves around the globe."
and then with a picture:



Gladych went on to explain that the reflectivity of the ionosphere was due to rays from the sun ionizing molecules of the atmosphere forming a conducting layer between 60 and 70 miles up.  As many ham radio operators know, this reflecting layer is a boon to radio communications in the high frequency range around 7 MHz, but higher frequencies like microwave communications at 144 MHz are not reflected back to Earth.  However, there are periods of intense solar activity that improve the 'reflectivity' of the ionosphere.  For more about this, see +Ian Poole's excellent article on sunspots and the ionosphere.

What the Air Force sought to do was create these enhanced ionospheric patches at will.  They assembled a team of researchers in Bedford Massachusetts, Dr. Frederick F. Marmo and his associates L. Aschenbrand, and J. Pressman.  Marmo and company reasoned that by creating an easy to ionize cloud, one made out of particulate phosphorous, they could deliver an ionosphere in a can.  And thus was born Operation Smoke Puff.

A launch pad for an Aerobee rocket was assembled in southern New Mexico, and a fifteen pound, (xxx kilo), clump of phosphorous was launched to an altitude of 60 miles where it was detonated.  Ham radio operators in a radius of 700 miles around the launch site were asked to transmit on frequencies between 7 and 144 MHz and submit reception reports on the quality of their communications.  Sure enough, the artificial ionosphere worked like a champ providing "next-door clear" communications for 45 minutes.


It Seemed Like a Good Idea at the Time
As it turned out, the 45 minute dispersion rate was a bit limiting, and there were other problems besides.  The invention only worked during daylight hours when there was sunlight available to ionize the cloud.  There were plans in the works for a night enabled version, but it had it's own issues.  While it was advertised as being very effective at confounding enemy radar, the cloud presented a bit of a defensibility problem in that it would have produced a visible light glow over the ground target it was protecting, easily pointing out its location for bomber pilots.  In the ever-optimistic 50's though, there was still an upside.  Gladych reported that

"for peacetime applications, the glow of a large and longer-lasting ion cloud could be used to illuminate a city better than the street lamps.
References:
1.  Gladych's article in Popular Mechanics
http://goo.gl/gZ72AR

2.  +Ian Poole article on sunspots and the Ionosphere in Radio Electronics
http://www.radio-electronics.com/info/propagation/ionospheric/sunspots-cycle-activity.php

3  Marmo's patent on expansions to the Operation Smoke Puff work
http://www.google.com/patents/US3052052

4.  Saving HAARP... You know, for the hams...
http://chipdesignmag.com/carter/2014/07/16/help-save-haarp/

5.  Newspaper article about operation Smoke Puff 4/18/1957
http://news.google.com/newspapers?nid=1314&dat=19570418&id=u7YyAAAAIBAJ&sjid=OecDAAAAIBAJ&pg=2136,371543
mentions Dr. O. G. Villard of Stanford who headed up the radar measurements of the cloud.

6.  Popular Electronics article enlisting listeners
http://www.americanradiohistory.com/Archive-Poptronics/50s/57/Pop-1957-06.pdf

also shown here:


7.  O.G. Villard on Operation Smoke Puff
http://www.americanradiohistory.com/Archive-Radio-News/50s/Radio-News-1957-06-R.pdf

Tuesday, July 15, 2014

Dynode Dawdling Lab Book 2014_07_14

Summary:
The photomultiplier tube on the NaI detector doesn't seem to be doing quite what it should.  There's a generally held belief, (when I say generally held belief, read, "a professor told me"), that the count rates aren't high enough.  Last week, the case of the tube was arcing to my hand making nice little static shock looking flashes of light.  Consequently, I spent today doing research on the three most likely PMT tubes that are housed within the detector.  Since the tube is surrounded by a mu metal magnetic shield, it can't be inspected to find it's exact type.  I have a call in to the company that purchased the original manufacturer, and hopefully they can figure out which kind of tube we have.  In the mean time, I've turned down the tube bias which seems to have stopped the arcing.  I've also inspected the voltage divider that provides the accelerating potential for the dynodes in the PMT.  This inspection could just as easily have stopped the arcing by moving a component away from the metal housing.  While the divider chain case was off I went ahead and drew a schematic of the circuit.  A partial Cesium137 spectrum was taken this afternoon and it looks promising.



New to the experiment?  Scroll to the bottom to see background and get caught up.

Lab Book 2014_07_14
Lab Book 2014_07_14     Hamilton Carter

I’m working on debugging the dynode divider which appears to have been damaged last week, probably by running too much voltage on the power supply attached to it.  I came across the following spectrum that looks great given the nature of the spectra that may be present in the experiment.  The prediction of the maximum possible radiated energy via h-rays does not mention anything about what the overall spectrum will look like.  If we have a maximum energy of 187 keV, we could also get radiation anywhere below that level.  In the following spectra from the Harshaw manual, you can see that the exact detector that is to be used can see radiation all the way down to the 32 keV Barium K X-ray line.


I found a thesis where the Harshaw 12S12/E was used.  We have a 12S12/3.  I’m not sure how they’re related yet.  In the thesis, a Dumont 6363 photomultiplier tube was used.    There is also a schematic for the dynode voltage divider chain that was used with the Dumont 6363. 



I’ll check these resistor values against the ones in the dynode divider if necessary.  I found a second thesis that mentions using a supply voltge of 900 rather than the 1000 Volts mentioned in the first thesis, (see the figure above).
I also found a paper that mentions the Harshaw 12S12/3 specifically.  The is the model that we have.  The paper mentions another key piece of information.  The aluminum housing of the crystal is 0.5 mm thick and is made of spun aluminum.  The window itself if listed as 0.010 inches thick at another web site.


On a mostly side note, this report is kind of interesting as to what is available for history of physics research.  It’s the equipment inventory for a nuclear rocket project performed by General Aerojet.
In this report, the PMT is listed as a RCA 8054.
In this LANL report written by Ellery Storm, the PMT is also listed as an RCA 8054.

This might be a good reference for supplementing with film detectors.  It was authored by Ellery Storm.

Resistor color code tool used to check resistor values:

Source mentioning that tube is in apparatus
Tube Type
Max Anode/
Cathode
Voltage
Max Consecutive Dyn V
2500 V
300 V

2000 V
250 V
1800 V
Not specified













The following pictures detail what the voltage divider chain being used to drive the PMT looks like:


This one details the high voltage input and its associated 55.6 ohm resistor.


This is a side view of the same input.  The identical resistors shown in the foreground are part of the dynode voltage divider chain, see the schematic below.


This picture continues along the divider chain.  Note the capacitors that are connected in parallel across the last few dynode resistors.  They are omitted in the hand drawn schematic below.


Finally, the green wire connects the plate/anode of the PMT to the pulse output that is used by the QVT.
A hand drawn schematic of the divider chain follows:


The pinouts of both RCA tubes and the DuMont tube are all identical and can be seen below.

Dumont Pinout



RCA Pinout

I setup the detector to take yet more data on the Cs 137 source this afternoon.  I’ll have the data in the morning.  Here’s what the spectrum was up to when I left for the evening.
The key difference here is that the tube is biased to 2000 V instead of 2600 V.  The arcing from the tube to my hand has stopped at this bias voltage.


The spectrum looks like it is already exhibiting two peaks after an hour or so of taking data.

Finally, a spreadsheet was made to calculate the voltages on the dynodes.  A sample output is shown below.


References:
These are some of the original source links for the reports mentioned above.  Since Word tries to open pdfs in Explorer instead of Chrome, all the links in the text are to Google Drive locations.

Ellery Storm report
I thought I remembered the name Ellery Storm and it turns out he wrote a book of stories about New Mexico.

Harshaw Manual

RCA 8054 manual original site:

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 



Monday, July 14, 2014

Rotational Instability in Pictures and Code

You might remember one of my G+ posts[2] from a few months ago, about a video wherein a Soviet astronaut spun a small wingnut,



OK, so not the Teenage Mutant Ninja Turtles character, an actual wingnut[3]:


+Bruce Elliott pointed out in a comment to the original post, (see below), that rotating an object, like a book, about its intermediate axis, (an axis parallel to the bottom edge of the cover), will cause unstable rotation.

Now, Brian Weinstein of The Fouriest Series[1] has posted a mathematica demo complete with gifs of the rotating book.  On top of that, he includes a link to a gist that contains the Mathematica code[4] for creating the rotation demo.

Here's the rotating book image from Brian's page, which I'd advise following if you enjoy mathy gifs!


G+ post mentioned above



References:
1.  Awesome intermediate rotation page
http://fouriestseries.tumblr.com/post/91685028535/rotational-stability

2.  G+ post
https://plus.google.com/108242372478733707643/posts/KxN4Dj55a7E

3.  Wingnut video
http://youtu.be/dL6Pt1O_gSE

4.  Mathematica code gist
https://gist.github.com/BrianWeinstein/6a8a852c46053c0c8d7d

Friday, July 11, 2014

Lab Book 2014_07_10 More NaI Characterization

Summary:
Much more plunking around with the NaI detector and sources today.  A Pb shield was built to eliminate cosmic ray muons as well as potassium 40 radiation from the concreted building.  The spectra are much cleaner, but still don't have the count rates or distinctive peaks that are expected.

New to the experiment?  Scroll to the bottom to see background and get caught up.

Lab Book
Threshold for the QVT is currently set at -1.49 volts.  Remember to divide this by 100 to get the actual threshold voltage.
A new spectrum recording the lines of all three sources, Cs 137, Co 60, and Sr 90, was started at approximately 10:55.
Took data for about an hour.

Started the Cs 137 only spectrum at about 11:55 AM


Here’s the no-source background from yesterday

In comparison, here’s the 3 source spectrum from this morning.


The three source spectrum shows peak structure not exhibited by the background alone.
I forgot to take scope pictures of the Cs137 run. I do however, have the printout, and will enter the data soon.

A Pb brick shield was built to calm down the background noise from cosmic ray muons, concrete K 40, and radon. 


The source is situated at the base of the NaI crystal as shown below:


The spectrum from a Co 60 source in the Pb bunker is shown below.  I’ll get the data entered soon.
The photo quality is poor, but I believe there’s a peak in the middle of the screen.

Finally for today, here’s the spectrum with the Pb bunker and no source.  Note that it’s much cleaner.


I've played one other trick here by using the linear output as opposed to the log output that was used in all the other plots.  It makes the spectrum appear more clean.



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