X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com X-Virus-Scanned: by amavisd-new (Uni-Kiel/l4ms-sc) From: geda AT psjt DOT org (Stephan =?utf-8?Q?B=C3=B6ttcher?=) To: John Doty Cc: geda-user AT delorie DOT com Subject: Re: [geda-user] OT: ballooning References: <54282517-6681-7931-7f10-23a9c4882f99 AT neurotica DOT com> <4733B1AC-D60F-42C6-A7AB-A3259D937A9B AT noqsi DOT com> Date: Wed, 05 Jul 2017 09:05:07 +0200 In-Reply-To: <4733B1AC-D60F-42C6-A7AB-A3259D937A9B@noqsi.com> (John Doty's message of "Tue, 4 Jul 2017 19:22:18 -0600") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by delorie.com id v6575Bv7028522 Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk John Doty writes: > On Jul 4, 2017, at 2:53 PM, Stephan Böttcher wrote: > >>>> No, sorry. What I have is for the RPi1. I hope to launch it on a >>>> balloon into the stratosphere next week: >>>> >>>> http://www.ieap.uni-kiel.de/et/people/stephan/rpirena/ > > I used to do that stuff a long time ago. Last time was 1975, with a > ton of gondola carrying NaI/CsI “phoswich” scintillation detectors for > hard x-rays. We sent it up with a 1.5 million cubic meter “zero > pressure” helium balloon. One of our students build a phoswich detector with a plastic scintillator inside and CsI outside, that flew on a Bexus mission. http://rexusbexus.net/ The CsI light yield was much higher than the plastic, and much slower. The digital filters could easily distinguish hits in CsI form only plastic hits. The plasitc hits were 100% neutral particles, gamma and neutrons. The most difficult part was the PMT HV at 25km altitude. She blew multiple preamps the thermal vac testing, until the HV isolation was ok. >> That slope can be the tail of the noise or indeed some x-ray >> background. It looks like the tail of the noise to me. > > Might also have some poorly collected charge. The outer edges of these > diodes are usually not depleted: you’ll collect some charge from a > track by diffusion, but you’ll lose some of it, too. Right, these photodiodes do not have guard rings to provide sharp edges of the sensitive volume. All our custom made silicon detectors have those. But there is still an edge. >> The light can be measured with the same kind of silicon >> photodiodes. The calibration is not as easy, since the light yield >> depends on temperature and doping of the scintillator, on the shaping >> time of the electronicsm and the resulting balistic deficit, which is >> the light that comes to late to be integrated by the shapers. The time >> profile of the light emission depends on temperature as well. > > In the old days we used photomultipliers. At least with diodes you > don’t have to worry about magnetic fields changing the gain! > > John Doty Noqsi Aerospace, Ltd. > http://www.noqsi.com/ > jpd AT noqsi DOT com -- Stephan