I'm forwarding these minutes from the last couple of inter-experiment
supernova working group meetings (now officially named SNEWS).
(BTW if anyone else from MACRO is interested in joining this group or
attending future meetings, I'll add you to the mailing list).
Kate.
===========================================================
Teleconference, April 28, 1999
-- Art McDonald reported on the status of SNO: the news sounds
extremely good. The connector breakdown problem was identified as
having to do with too-highly-degassed water and flushing with nitrogen
has greatly diminished it. Water fill is very nearly completed, and
within a week they'll be able to begin to study the detector
properties in preparation for supernova detection work. They expect to
be able to contribute real alarms within some months.
-- LVD, MACRO and Super-K are all online now (status more or less the
same as previously reported), sending automated alarms. There's not yet
any actual alert to astronomers.
-- Also, there's no direction information as yet (either individual
experiment or triangulation). It's not yet decided whether the
experiments will eventually send their individual direction information
via the network.
-- Alex Murphy reported on a possible collaboration between MINOS and
OMNIS, to use the MINOS far detector as the active mass for neutron
detection. They're going to have meeting in early May. Stay tuned.
-- We discussed the privacy agreement. Everyone more or less agrees
with the general format. Art M. suggested that we refine the wording to
make people more comfortable, emphasizing the reasons for wanting
privacy (people don't want their data analyzed), and making more
explicit prohibitions. We should make it into a document (some kind of
memorandum of understanding) that we can present to our collaborations
to be blessed. Mark V. suggested that subgroup members should sign a
physical piece of paper stating that they agree to the privacy
conditions.
-- We discussed the new organization on kaboom: working, repository and
real alarm areas, and passwords for the working and web areas were
dispensed. Passwords will be changed regularly. Everybody is OK with
using cvs as a code development sharing tool. I'll be posting info on
the working group page about working with cvs later today (along with
more code docs).
-- We went through the job list on the web pages. Several people expressed
interest in helping out. Some notes on the individual items (and issues
that came up while discussing them):
* Secure sockets: should be straightforward.
* PGP signing of alarm messages: straightforward to implement.
Art M brought up: we ought to make sure that astronomers will be happy
with the credibility of our alarms; this includes security (which is
important), but goes beyond that to include general reliability.
Perhaps we should seek some kind of formal acceptance by the
astronomical community, after a series of tests and perhaps some kind of
review procedure? The AAS meeting may be a good venue (organization
for sessions for the January meeting is happening now.)
* Alarm retraction: straightforward to implement. May need some work
on the part of the individual experiments to incorporate into the
individual alarm systems. Art M. pointed out that this means that we
have a second level of human-checked alarm; astronomers may opt to wait
for confirmation. This is probably inevitable.
* Multiple servers: straightforward to implement. We can have multiple
servers either for 1. extra security check for alarms, or 2. redundancy
in case a server is down (but not both? Should it be an AND or an OR?).
* Anti-coincidence and consistency check: slightly tricky to implement,
but do-able. An important question is: how do we define our coincidence
criterion? Right now, the configuration is simple: 3 experiments, no
consistency check, 2/3 coincidence for alarms. But what about, say, 4
experiments, which get pinged for alive-or-dead. Do we require all
experiments which say they are live to have a consistent signal? 3/4?
To refine our coincidence criteria, we may need a lot more
inter-experiment discussion. But, this is really a second-order
problem; to first order all experiments (LVD, SNO, MACRO and Super-K)
have the same sensitivity in terms of numbers of supernova candidate
stars. In any case, there's no reason not to go ahead and do the
technical implementation of the post-coincidence experiment query.
Another point: for any individual experiment the "I am alive" criterion
must mean "I would have been sensitive to a signal in the Galaxy during
the time period". This is the responsibility of the individual
experiments, and may be some work (but then so is an online monitor).
* We need to think about how to do the timing tests; it's not
completely obvious how to proceed. In principle, if experiments have
GPS or equivalent it should "just work". But it's not clear how to test
the whole system, starting from light in the detectors. Clarence V. knows an
atomic clock expert who may be able to lend experience; others may also
have thought about this problem.
* Art M. suggested that we need a generally well-defined test plan.
* Mark V. will implement some preliminary triangulation code.
* We also ought to think about keeping track of how good network
connections are, over the next year or so, to decide if we need to
upgrade the system to dedicated phone lines.
-- We all agree that SNEWS is OK for our name. Let's make it official.
-- Preliminary time of next working group meeting: May 26, 10 am EDT.
SNO and Super-K both have collaboration meetings in early June and it
would be a good thing to have a formal privacy agreement by then. Since
teleconference is a difficult format for non-native-English speakers, let's
make the effort to have a videoconference next time.
============================================================
Video meeting, May 26, 1999
Represented experiments: SNO, Super-K, MACRO, LVD, AMANDA, OMNIS
News from experiments:
---------------------
-- Alex Murphy reported on a meeting between the OMNIS and MINOS
collaboration. He said that the outcome was quite positive; the MINOS
collaboration is willing not only to consider alternative analyses,
but even to consider modification of their detector design. There is
some possibility of inserting Gd-loaded sheeting in the air gaps
between the scintillator/iron planes. Cost would be in the $100,000
range, to be installed by the start of running in 2002.
-- SNO running is going well; the connector problem remains quashed.
They are sealing against radon.
-- AMANDA will report on a new SNMP (their supernova rate monitor
hardware) analysis at the upcoming ICRC conference. They are working
on an SNMP hardware upgrade. Also 6 new strings will be deployed this
summer.
-- SK, LVD, MACRO: no change in status. There will be no Super-K
upgrade down-time this summer.
Privacy agreement:
-----------------
There were a couple of suggestions for modification:
-- Art M. proposed adding an additional group (an "advisory board"
for lack of a better name) consisting of senior level members from
each experiment, whose function is to "authorize" the members of the
subgroup, decide the high-level security issues, and make it all
official. Everyone agreed that this is a good idea.
-- Another suggestion was to keep a cap on the number of members
of the working group, to keep it down to a manageable size (although
this is not yet a problem.)
I'll modify the draft according to these suggestions and post it
shortly. SNO, LVD and Super-K are all having collaboration meetings
at the beginning of June, which is a good opportunity to have
the privacy agreement approved by the different experiments, and for
an advisory board to be formed.
Time synchronization tests:
--------------------------
I gave a short talk on the "LED time bomb" possibility described in
my previous email. There were several comments and suggestions.
-- There are really two things we'd like to test:
1. Whether each experiment is tagging the event times right,
and
2. whether the whole alarm coincidence system is working, starting
from light in the detector, to the individual software burst monitors,
all the way to the coincidence server and alarm.
For #1, you only need a single LED time bomb that could be
shuttled around from experiment to experiment. Also, a simple
light signal, e.g. a single LED, would be sufficient here.
#2 is harder -- to test several experiments at a time, we need at
least two and preferably more bombs. It's also trickier to set up,
because to test the whole system, you need some kind of stellar
collapse simulation in each detector plausible enough to pass the
software tests (e.g. position uniformity tests for SK and MACRO).
Both LVD and AMANDA reported that they are not currently well set up
to split LED signals. So rigging this test may require hardware
tinkering and/or software twiddling on the part of all experiments --
but may be doable.
Of course, we could do these two tests separately; for a test
of #2, you only really only need timing good to ~seconds.
So maybe we could have several cheap time bombs for #2 and
a single shared high stability time bomb for #1?
-- Clarence V. has spoken to his NRC contact, Rob Douglas at NRC,
whose timing expertise we may be able to draw on. One point was that
a single timing test isn't enough; we will have to keep checking
whether things stay in synch. Experience will show what a reasonable
interval is. We could also look into whether it's possible to borrow
an atomic clock from NRC (a single clock would be good enough for
individual experiment timing tests.) He may have other good ideas.
-- Adam B. pointed out that the time window for a coincidence test
with AMANDA is only a 3-month period during the austral summer (Dec-Feb).
We should consider this when scheduling multi-experiment tests.
-- Ludwig dB. of Duke U. pointed out (by email later) that the
relativistic effect on an airplane is ~0.1 microsecs/day. If we're
lucky enough to get a clock good enough for this to be a problem, we
may need to make corrections!
Next meetings:
-------------
We agreed that another video meeting in about 2 months would
be a good idea. We should also aim for a physical meeting in
the fall.