Gluing procedure for BGO, fast and slow scintillator Mózsi Bank Kiss & Tomi Ylinen Nov. 23, 2005

In the gluing procedure explained here, the following items are used: 1.Aluminum support structure 2.Aluminum support pieces 3.Teflon tape, red tape and double sticky tape 4.Latex gloves 5.Polyurathane adhesive 6.Scale 7.Syringes with and without needle 8.Test tubes with lids 9.Centrifugal unit 10.Beaker 11.Q-tips 12.Lint-free paper 13.Isopropyl alcohol (IPA) Before you start

Polyurethane adhesive HE E-Z Kit Adhesive with HE 4 AntiFoam Supplier: Hartel Plastics – F, Branford Pacoima, CA To prevent allergic reactions, similar to the effects of poison oak, use gloves at all times!

Aluminum support structure (1) In order to correctly fit the support pieces onto the aluminum support structure, the following procedure should be used: Clean all aluminum surfaces with isopropyl alcohol Put double sticky tape on the side of the support piece that goes against the aluminum support structure and put two very small pieces on the sides of the support piece that face the BGO Attach the support piece to the BGO as seen in the figure below Push the BGO + support piece gently towards the broader side (1) and the bottom of the support structure (2) and then finally towards the narrower side of the support structure (3) Gently remove the BGO and the two small pieces of tape Repeat for fast and slow scintillator and align the three components by putting red tape on the support structure and pieces as needed support piece tape aluminum

Use teflon tape at the joints to prevent the glued components from attaching to the support structure Aluminum support structure (2) 13 mm

Preparing polyurethane adhesive (1) Put a beaker on the scale and reset. Pour up 10 g of component “A” Add 8.5 g of component “B” Add 3 drops of AntiFoam using the pipette When components A and B have been mixed, the adhesive should be applied within 25 – 40 minutes

Preparing polyurethane adhesive (2) Stir the adhesive and pour into a test tube. Make sure to use gloves! To remove bubbles, a centrifugal unit should be used. Insert the test tube in the unit and insert a counterweight tube of about equal mass on the opposite side Close the lid and centrifuge for 10 minutes. While waiting, clean the uncoated surfaces of the BGO, the fast scintillator and the slow scintillator (inside and outside) with isopropyl alcohol and lint-free paper. The inside can be cleaned by pushing an IPA-soaked paper through the tube with a stick.

Preparing polyurethane adhesive (3) It is important to use the centrifugal unit and remove as many bubbles as possible from the adhesive before application, since these grow during curing…

Gluing the BGO and the fast scintillator Use a disposable plastic syringe (without needle) to draw about 0.2 ml of the adhesive from the tube Apply about 0.08 ml on the center of the BGO Press BGO and fast scintillator together. Move around in a circular motion to spread the adhesive evenly. Gently wipe off excess with Q-tips

Placing the glued components in the support structure Carefully place the glued components in the support structure according to the figure below, which shows a slice of the support structure as seen from above. Press the fast scintillator from above to remove the bubbles from the joint. Inspect the joint through the fast scintillator and make sure it is free from bubbles. Place rubber bands around the structure at the support pieces as seen in the picture. 123 aluminum

Gluing the slow scintillator If the adhesive in the test tube has formed bubbles at this point, centrifuge the tube for an additional couple of minutes. Dip the needle of the syringe into the adhesive in the test tube and spread evenly on the edge of the slow scintillator. Avoid “whipping” motions with the needle, since these may induce bubbles in the adhesive. To avoid getting air in the joint, which will reduce the light transmission, it is better to use a little too much adhesive than not enough adhesive. An even layer of 1 – 1.5 mm should suffice.

Placing the slow scintillator in the support structure Turn the slow scintillator so that the adhesive is downwards and place it in the support structure as indicated in the diagram below. Press the slow scintillator from above to remove any remaining bubbles and place rubber bands around it to lock it to the structure. 123 aluminum Place some weights on top to maintain pressure. Allow adhesive to cure overnight or preferably longer.

Cut grooves in the aluminum support structure to prevent glued parts from sticking to the structure. It would also be good to cut some additional holes in the structure, so that the glued joints can be viewed from all directions. Suggestions for improving the procedure before after

Artist’s impression © 2005, Tomi Ylinen The End