Intern Experiments Taking Shape

It's been a while since we've updated all of y'all on what's happening, so let's get up to date!

CR-39 Oriani Replication

Well, ordering everything was a bear, but all of the materials have finally arrived. The glass cell, cell clamp, Mylar, lithium sulfate, NaOH, and Pt wire all showed up last week, so I cut a few dummy 3cm x 3cm chips out of polycarbonate to make a mock-up of the cell. The cell is put together exactly as laid out in the procedure document, only I used the polycarbonate chip instead of CR-39. The first time I put the cell together I used a sheet of Mylar roughly the same size as the chip, and the cell had a small leak. The second time, I used a large sheet of Mylar that hung out over the edges of the chip and the cell was watertight (I left water in it for a week and didn't lose any). Also last week, I wound the electrode wires into crude flat "spiral pancakes" that will be held 10mm apart within the Li₂SO₄ electrolyte solution. We have decided that in order to protect the Ni wire from the electrode, the wire will be inserted into a glass capillary tube (ID- 0.5mm) and the end sealed with a flame. Exposing the Ni wire to a flame produces discoloration in the wire that is likely oxidation or carbon deposit, but since DC current travels through the bulk of the wire we have decided that this should not hinder the experiment. If we find later that it does hinder performance, we can either sand down the discolored areas or we can seal the glass tubes with silicone. The Pt wire will not be sealed in a glass tube as very little of the wire that isn't part of the spiral will actually be exposed to the solution. The electrode wires will then be crimped, outside of the electrolyte, to copper wires that run out of the cell through the rubber stopper and get hooked up to the leads on the power supply (Pt to positive terminal and Ni to the negative terminal).

The CR-39 finally arrived yesterday. The material that we're going to be using is called TasTrak© from Track Analysis Systems Ltd. in Bristol, UK, and it came in 2 sheets, approximately 12"x10" pre cut into 66 3cm x 3cm squares and pre-etched with identification numbers from 001 to 112. From this point on, the "front side" of the chip will always be the side with the etched numbers, this side will always face the electrode during experimentation. Immediately after the chips arrived, I punched out two of them (they have to be punched out of the larger sheet they were cut from) and stored the rest, still in the radon-proof bag they were shipped in, in the freezer (as is recommended by the manufacturer). One of the chips (001) was set in the open air overnight in the same area where the experiment will be performed to get a background radiation level in the room. The other chip (002) was placed inside of a Ziploc© freezer bag in direct contact with a radioactive Americium sample; this was done as practice for etching and counting tracks on the CR-39, as the chip will (should) have track marks on it.

This morning, the etching process was undertaken. The two control chips (001 & 002) were etched along with chips 003 & 004. 003 and 004 will be used in the live cell and control cell, respectively, and they are being etched so that any track marks already present on the chips can be counted before experimentation and subtracted from the post-experiment total, effectively eliminating the significance of inconsistent chip problems. Approximately 200mL of 6.5M NaOH was prepared in a 250mL beaker and placed on a heated stir plate. All four chips were then hung with Ni wire from a ceramic rod placed atop the beaker. The chips were positioned in the solution so that none of them were touching each other, the sides of the beaker, or the magnetic stir bar at the bottom. The solution is being kept in the ~70-80^oC range (keeping the temperature strictly regulated is extremely difficult with nothing but a potentiometer knob controlling heat input). After the chips have been etched for 6 hours, they will be removed, washed, and immediately covered in several layers of Al foil. This foil will stop any stray particle contaminants from puncturing the chips and creating unwanted tracks. Chips 001 & 002 will be placed under the microscope and the tracks will be counted, hopefully giving us experience in the counting process and a feel for the background radiation. Chips 003 & 004 will be kept in their Al foil and placed with rest of the chips in the freezer until they are used for the experiment, which will start on Monday (I am out of town Thursday and Friday for a wedding).

Update! After leaving the chips etching for 4 hours in the vent hood at the local high school, I went back to find that our hot plate had heated the solution much too hot, approximately 75 mL had evaporated from the solution and the top corner of each chip was no longer submersed in the solution. The solution was at 100^oC when I got there, and as a result, the chips were etched too much. It can be seen under the microscope that the pits caused by particles were extremely rounded and had no definition, as happens with excessive etching. Also, there are diagonal lines across the corners of the chips that resulted from the slowly evaporating solution covering less and less of the chip. Unfortunately, the Supereyes microscope camera was not set up and pictures of the chips have not yet been taking, but they are on their way. 

I apologize for my absence, but I'll be back on Monday ready to rock and roll!

Stay tuned for more action!

Piezonuclear Experiment (Rock Crushing) - Carpinteri Replication

With the plates for the press welded, detectors on site, and rock samples cut we have begun the crushing process! To get acquainted with the press I've been testing out the procedure using rocks taken from the area. I jump every time the rock finally cracks.

The main goal of these tests is to practice before using the granite samples and see if we get any shock bubbles from ordinary rocks. Speaking of shock bubbles, we have performed a series of shock tests looking for bubble formation. The most forceful of these tests being holding the detectors on a steal table and hitting the table with a metal mallet. So far the only bubbles we have seen have come from background radiation, usually after being left out overnight. At the very least this makes any bubbles we get while performing the experiment more meaningful. 

Today the focus has been on creating a webcam setup that will allow us to record from multiple angles using multiple webcams. The cameras are limited by the length of the usb cable making it difficult to zoom in on the detectors, and the program we are running has crashed on multiple occasions. There were two successful runs this afternoon, but were done from a distance where the detectors were not in focus. 

Progress is being recorded in my original document below which now includes plenty of pictures to walk you through the experiment! I will continue to update this daily.