Instructions for Creating Pin Sources
I. Materials Needed
Before mounting pin sources, it is helpful to gather all the necessary materials:
- lay down thick paper towels on the table
- two tweezers: use what is most comfortable for you. The best for me was to use one with a thin, curved mouth and a second one with scissor-style opening. See pictures below.
- needle-nosed pliers
- set of metal slides, cleaned with acetone, in boxes with numbered slots
- thin plastic case to hold slide steady while mounting
- liquid super glue (not gel!)
- radiation meter (Betty has a digital one)
- finally, get the bundle of pin sources from Pete Griffins / Becky DeZess in ORCBS.
II. Creating Bundles
Bundles of pin sources must be made at least 24 hours in advance. Check that Pete or Becky will be around when you want to put the pin sources into the irradiation machine, usually they leave by 4 pm.
Put together enough pins for all the slides you will need, plus extras. The irradiator cannot take more than around 30. It is helpful to set the pins upright in a nut, to hold them together. Then you can take a small-gauge wire (not extremely small) and wrap it tightly around the pins. Twist the two ends with needle-nose pliers until the wire grips the pins and holds them together. Be careful, twisting the wire too much will cause it to snap. Now you can remove the nut and wrap the bundle with wire a second time. This should be enough to hold the pins together and keep any from falling out.
Trim off the wire ends, to enough room for the pins to go into the irradiator. You may need to bend the ends to fit.
Mark one side of the pin sources with a colored Sharpie. Ask for the non-colored end to be irradiated. Then when mounting the colored end of the pin will go into the groove of the slide.
III. Mounting Pin Sources
Mounting the pin sources is a two-person job. Remember the pins are radioactive! Gloves should be worn while handling hot pin sources.
The first person should hold the slide onto the lip of the plastic case; this will keep it steady and level during the mounting process.
The second person should use the scissor-like tweezers to pick up a pin while the first person sets a drop of glue into the groove.
Set the colored end of the pin into the groove of the slide. The first person should now use the curved tweezers to pinch the end of the pin against the slide.
The second person can hold the pin in place with the scissor-style tweezers. We used a shallow box so that we could rest the tip of the tweezers against the bottom while holding the pin in the groove.
Keep the pin straight until the glue begins to set (30-60 seconds) but let go before it dries completely. The pin should be in the plane of the slide; if any part is above or below the metal slide it can damage the silicon strips. Gently push the pin with your tweezers until it lies within the plane. Allow the glue to dry completely, with the slide horizontal, before storing it vertically in the tray.
IV. Testing Pin Sources
Before using the pin sources, you should measure the radiation with the digital radiometer. Pins reading higher than 300 cpm at 5 cm away may be too strong. Record the radiation level at both 5 cm and 1 cm away along with the corresponding number on the plastic pin source holder. Later, record the telescope number corresponding to each pin source number.
Before you throw anything out, remember that anything that has touched the pin sources may now be radioactive. Test your materials, even trash, with the radiometer before putting them away. The half-life of the pin sources is short, so you can store radioactive items in the safe for a few days and retest them later.
