[ RadSafe ] Optical Couplant

[alstonchris at netscape.net]

Syd

Well, like I said, it's in research-grade detectors that the direct mating is done (to maximize resolution).  And yes, all seals fail eventually (if a crystal is turning yellow inside a supposedly hermetically sealed detector, it's a sign that moisture has gotten in, i.e., the integrity of the seal is compromised), but detectors can be renewed.  Also, I think that it's not so much the NaI that's toxic, but the doping thallium.  If one were to dispose of a crystal oneself, one would need to do so as hazardous waste.  Which is why it's better to simply return it to the manufacturer/vendor.


Cheers 
cja


-----Original Message-----
From: AnaLog Services, Inc. <AnaLog at logwell.com>
To: Edmond Baratta <edmond0033 at comcast.net>; alstonchris at netscape.net
Cc: radsafe at radlab.nl
Sent: Wed, Oct 28, 2009 1:52 am
Subject: Re: [ RadSafe ] Optical Couplant


As far as I know, it is rare to have naked crystal material coupled directly to the PMT face. At least it is rare in my industry. I have seen it, but only a couple of times. NaI is quite hygroscopic so dealing with bare crystal material except in a special facility is problematic. I believe NaI is regarded as toxic also. 
 
Heck, we have problems with crystals turning yellow even in the hermetic containers. 
 
Syd H. Levine 
AnaLog Services, Inc. 
Phone: (270) 276-5671 
Telefax: (270) 276-5588 
E-mail: analog at logwell.com 
Web URL: www.logwell.com 
 
----- Original Message ----- From: "Edmond Baratta" <edmond0033 at comcast.net> 
To: <syd.levine at mindspring.com>; <alstonchris at netscape.net> 
Cc: <radsafe at radlab.nl> 
Sent: Tuesday, October 27, 2009 8:11 PM 
Subject: Re: [ RadSafe ] Optical Couplant 
 
>I believe only the older ones were coupled. Most of the newer ones are >coupled directly and sealed. The manufacturers used to supply (sell) the >material to couple the older ones. 
> 
> Ed Baratta 
> 
> edmond0033 at comcast.net 
> 
> -------------------------------------------------- 
> From: <alstonchris at netscape.net> 
> Sent: Tuesday, October 27, 2009 6:10 PM 
> To: <syd.levine at mindspring.com> 
> Cc: <radsafe at radlab.nl> 
> Subject: Re: [ RadSafe ] Optical Couplant 
> 
>> 
>> Syd 
>> 
>> Is there nothing in Knoll (Radiation Detect and Measure) that's useful on >> this subject? Also, e.g., research-grade NaI crystals are mated directly >> to the PMT, no? 
>> 
>> Cheers 
>> cja 
>> 
>> 
>> -----Original Message----- 
>> From: Syd H. Levine <syd.levine at mindspring.com> 
>> To: J. Marshall Reber <jmarshall.reber at comcast.net> 
>> Cc: radsafe at radlab.nl 
>> Sent: Sat, Oct 17, 2009 10:16 pm 
>> Subject: Re: [ RadSafe ] Optical Couplant 
>> 
>> 
>> I looked for something, even qualitative, and could not find anything >> interesting. I found some stuff related to fiber optics that surprised me >> (not as big an improvement as I expected), but I do not know how that >> applies to scintillation detectors. I do not *think* a scintillation >> detector will work at all without coupling compound. 
>> 
>> Syd 
>> 
>> ----- Original Message ----- From: "J. Marshall Reber" >> <jmarshall.reber at comcast.net> 
>> To: "Syd H. Levine" <syd.levine at mindspring.com> 
>> Cc: <radsafe at radlab.nl> 
>> Sent: Saturday, October 17, 2009 3:48 PM 
>> Subject: Re: [ RadSafe ] Optical Couplant 
>> 
>>> 
>>> On Oct 17, 2009, at 4:21 PM, Syd H. Levine wrote: 
>>> 
>>>> I finally got around to writing a page about optical coupling >>>> compounds: 
>>>> http://www.logwell.com/tech/servtips/optical_coupling_grease.html 
>>>> 
>>>> Comments or criticisms needed and much appreciated. 
>>> 
>>> It would be useful to quote in quantitative terms the actual light > >>> transmission improvement of using the coupling compounds. 
>>> 
>>> Unfortunately I am unaware of such data. 
>>> 
>>> J. Marshall Reber, ScD 
>>> 165 Berkeley St. 
>>> Methuen MA 01844 
>>> 
>>> Tel/Fax: 978-683-6540 
>>> Alternate Email: reber at alum.mit.edu 
>>> 
>>> 
>>> 
>>> 
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> 
>