Search found 8 matches

by wraith_oz
27 Mar 2017, 09:02
Forum: Shielding
Topic: New Shield
Replies: 18
Views: 11006

Re: New Shield

I would have made a round shield but couldn't find anything suitable to use as molds to form the lead. The melting point of lead free pewter is less than that of lead hence you can't use a pewter tube as a mold unfortunately. Make sure that the shield you make is large enough for a Marinelli beaker ...
by wraith_oz
09 May 2015, 10:48
Forum: Shielding
Topic: New Shield
Replies: 18
Views: 11006

Re: New Shield

Alloys won't work particularly well. The reasons for a graded shield (sorry if I'm teaching you how to suck eggs btw) are that external radiation generates fluorescent x-rays in the lead shield. These have an energy of about 85 keV. The cadmium(or tin) layer is needed to block these but in doing so ...
by wraith_oz
08 May 2015, 09:15
Forum: Shielding
Topic: New Shield
Replies: 18
Views: 11006

Re: New Shield

Boris The counts/second also depend on the detector one is using. If your detector is larger or more sensitive than mine you wouldn't expect to see the lower count rate. However better shields may help. I attached a spreadsheet to my original post which enabled the calculation of the performance of ...
by wraith_oz
08 May 2015, 09:07
Forum: Shielding
Topic: New Shield
Replies: 18
Views: 11006

Re: New Shield

G'day Karl Yes that is correct, the background rates dropped from about 100 counts/second to 3.6 counts/second for no shield and with shield respectively. I realised once construction had started that I wouldn't be able to use a Marinelli style container. But thinking about it, to be able to use one...
by wraith_oz
04 May 2015, 19:25
Forum: Shielding
Topic: New Shield
Replies: 18
Views: 11006

New Shield

Having finally got some time to devote to gamma spectroscopy and collected most of the hardware required, the design and construction of a shield was considered a priority. Some time was spent searching for information and pondering what it all meant as well as finding out who sold pure lead in my p...
by wraith_oz
03 May 2015, 19:15
Forum: Introductions
Topic: G'day everyone from John
Replies: 7
Views: 2819

Re: G'day everyone from John

Welcome John! Let me know if you need any help with the LYSO build. I've had best resolution results using just a single crystal head-on. Of course Luuk says he gets very good resolution also from a small array, but after all, he is Luuk! :) Cheers, Tom Thanks Tom. I'll bear that in mind. Regards J...
by wraith_oz
03 May 2015, 07:42
Forum: Introductions
Topic: G'day everyone from John
Replies: 7
Views: 2819

Re: G'day everyone from John

I intend writing it up and have in fact started with a schematic diagram for the electronics using DesignSpark but not having a great deal of experience with it it is proving to be a bit of a challenge to say the least! By the way, can we post attachments other than images on this forum, pdf for exa...
by wraith_oz
02 May 2015, 21:04
Forum: Introductions
Topic: G'day everyone from John
Replies: 7
Views: 2819

G'day everyone from John

Another one from the old forum. By way of introduction I am retired now and have been so for nearly a year. I was an industrial chemist once working in the paper industry but have spent the last nearly 40 years in the mining industry (kaolin, tin, gold, diamonds, silver/lead/zinc and copper), initia...