Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!sdd.hp.com!hp-pcd!hplsla!tomb
From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: Can anyone identify these tubes?
Message-ID: <5170084@hplsla.HP.COM>
Date: 31 Jul 90 18:06:32 GMT
References: <1624@oucsace.cs.OHIOU.EDU>
Organization: HP Lake Stevens, WA
Lines: 6

Considering that Jarrell-Ash made it, and the "hollow cathode"
description, the second tube is probably one that emits spectral
lines of those elements, for calibration of an optical spectrometer.
J-A makes (made) spectrometers and associated equipment.  And that
would say that the first one is indeed probably a PMT or a photodiode
(not solid state ;-).  (My PMT book is at home; can't look it up.)