Forwarded query

[Tim Abbott]

	 Very sad news about Walter Kosonocky.  I enjoyed his
retrospective at Garching and I feel honoured to have met one
of the originators of our field before this tragic loss.

	If I may echo John Geary's sentiments, Walter's talk was
the capstone on a very successful workshop - many thanks to Jim,
Paola et al. for organising it all.  Also, many thanks to Fred 
Harris for broadcasting his most extensive notes, these are now
available on the CCD-world web page (new URL: 
http://www.cfht.hawaii.edu/~tmca/CCD-world.html).

	In the meantime, I pass on the following interesting query
about a possible alternative application for CCDs.  Perhaps it will
provide a diverting idea for some of us.

	Best regards,

		Tim



Georgios Skillas writes:
>From skillas at solid.phys.ethz.ch  Wed Oct 30 05:18:13 1996
Message-Id: <199610301514.QAA28484 at solid.phys.ethz.ch>
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Date: Wed, 30 Oct 1996 16:16:52 +0100
To: ccd-world-request at cfht.hawaii.edu
From: skillas at solid.phys.ethz.ch (Georgios Skillas)
Subject: Info about the CCD mailing list.
Cc: skillas at solid.phys.ethz.ch

Dear Sir,

although I am not a astronomer or IC technology expert ( I am
working on my PhD. on aerosol characterisation ) I would like
to obtain some information about CCD technology which will
enable me to judge if a CCD-like device would be a solution to
the following problem :

To get information on the particle mass of charged aerosol par-
ticles (typical radii : 2 - 150 nm, typical charge : 1 - 2 electrons ty-
pical densities : 1000-2000 kg/m^3 ) are accelerated to near-sonic
( but always subsonic ) velocities and then led against a metal
plate with a radius of 1 cm. This metal plate is connected to an
electrometer, so one can count how many particles are impa-
cted. The noise level is between 3 - 10 fA while the signal is
typicaly between 30 - 600 fA. The electrometer time constant
is 4 s. As it is this device can only be used to characterise aero-
sols with high particle concentrations, and a lot of time is nee-
ded for each measurement ( ca. 30 min ) in order to obtain a
good statistic I am looking for ways to improve the device. On
the plus side, the plate is easy to clean, as it can be cleaned by
CH3COCH3 ( acetone ) or CCl4 ( carbon tetra cloride ) and even
ultrasound.

My question is : Could I use a CCD camera to obtain a better
temporal resolution as well as a lower noise level ? I could
live with a smaller plate radius, and what I need in principle
is a very accurate way of counting charges. It should be possible
to clean it by one of the aforementioned methods though.  If a
CCD does not work as is, could a partially completed CCD chip
( without the photon to electron conversion layer(s)  ) be used ?

I would be glad if I could post this question to the ccd-list.

Yours sincerely,

George Skillas




-- 
Timothy M. C. Abbott                http://www.cfht.hawaii.edu/~tmca/tmca.html