HDTenEightyP/NetNews huggingface dataset:
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: SSC magnets - how?
Date: 7 Apr 92 19:50:30 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa2.lbl.gov
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4   

In article <8400007@trsvax>, pauls@trsvax.tandy.com writes...
> 
>AnotherSSC question:
> 
>1) How many magnets are used?

Thousands of long (17-meter) dipoles and thousands of focussing quadrapoles.
A smaller number (many hundreds?) of correcting magnets (sexapoles), and of
course two monster solenoids for the two big detectors, and a variety of
specialty magnets such as final-focus magnets and extractors.  

> 
>2) In relative terms, how do they compare to other magnets in use today?
> 

They are very high field (roughly 6 Tesla), very uniform and very large.
Nothing like them has ever been built before.

>3) What is MBTF of a magnet today (FermiLab)?
> 

Don't know the specs of the Tevatron magnets. Sorry.

>4) How many 'up days' (up hours??) does the average collider have today?
> 

Now there's a loaded question if I ever heard one.  It very much depends on the
specific machine.  CERN, for example, has a reputation (well deserved) for
excellence.  When the SPS MCR (main control room) tells you that you will get 
beam at 9 am on April 6, then you don't have it at 8:59, and you will have it
by 9:01.  U.S. machines are often not so good.  I have never had a run at the
Bevalac with the machine actually running more than 50% of the promised time.
Magnets trip off, power supplies blow up, control electronics fail,
safety-interlocks trip at random, power generators fail, etc. The AGS 
(Brookhaven) has similar problems especially in the warmer months when
everything starts to overheat.  These are complicated machines, and are 
difficult to keep running.  In the end you get the beam you need, but it's
always an adventure.

In addition to down-time during your supposed beam-time on-target, the typical
machine has a maintainance schedule (one day a week down for repairs, for
example), and machine development time which can be large blocks of time, such
as weeks or months.  The Bevalac shuts down for a few months every summer,
partly because of the cost of electricity in the summer months, but also to do
needed repair.  In addition, a few days every couple a weeks are scheduled 
for routine testing of new beam-tunes, etc.  

I don't remember exactly, but the Bevalac has something like 2500 hours of
scheduled running each year.  Roughly half of that is for medical treatment of
cancer patients and others.  The rest goes to nuclear science experiments.
At more modern machines such as the Tevatron, almost all of the beam-time
will go to the high-energy experimentalists.

>5) If a SSC magnet goes fubar, is the whole thing down?

Yup.  Bummer.  But the magnets will be very reliable according to the experts.

-Scott

Newsgroups: sci.physics
From: a722756@pan.mc.ti.com (W. D. Rolph)
Subject: Re: Fusion reactor disasters --- impossible
Organization: Texas Instruments Materials and Controls Group
Distribution: na
Date: Mon, 6 Apr 1992 14:20:42 GMT


In article <FRANL.92Apr3132432@draco.centerline.com>, franl@centerline.com (Fran Litterio) writes:
|> In article <69672@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
|> 
|> > Moreover, you don't have
|> > nasty by products like radioactive cesium and iodine that would come from
|> > a leak. You may have some tritium and some induced radioactivity from
|> > structural components, but again, the total inventory is much smaller.
|> 
|> Isn't liquid lithium forseen as the medium used to absorbe the
|> neutrons speeding away from the fusion reaction?  The
|> (themodynamically) hot lithium would heat pressurized water that would
|> eventually drive steam turbines to make electricity.  Over time the
|> lithium becomes radioactive and needs to be replaced.  Being a liquid
|> would actually make it harder to manage the storage of waste over many
|> decades (in general, liquids leak, evaporate, corrode containers, etc.
|> more easilly than do solids).
|> --

If I am not mistaken, it depends on the type opf fusion reaction you hope to
pursue, D-D, D-T etc.
-- 

Regards.
 
Don Rolph  a722756@pan.mc.ti.com WD3 MS10-13 (508)-699-1263
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Asimov
Summary: died today
Date: 6 Apr 92 13:03:33 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

I heard on the news that Isaac Asimov died today.  Obit in Tuesday NYTimes?

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)
Newsgroups: sci.physics
From: brahm@cco.caltech.edu (David E. Brahm)
Subject: Re: Right handed neutrino
Summary: Majorana masses violate quantum numbers
Organization: California Institute of Technology, Pasadena
Date: Thu, 9 Apr 1992 01:58:02 GMT

vijay@wiliki.eng.hawaii.edu (Vijay Fafat) writes...
> Suppose the neutrino HAS a non-zero mass and suppose I see a left-handed
> neutrino going.  I decide to overtake it... do I get a LIGHT right-handed
> neutrino?

If you give the neutrino a Majorana mass (as is done in the usual see-saw
mechanism), then when you overtake the light left-handed neutrino you will
see a light right-handed antineutrino!  The see-saw theory also contains a
heavy right-handed neutrino and its antiparticle, a heavy left-handed
antineutrino, but these do not appear in your "experiment".

The trick here is that Majorana masses violate any quantum number which the
particle carries (here, e.g., lepton number), so "particle" and
"antiparticle" are not as well-distinguished as we normally imagine.  If
the electron had a Majorana mass (instead of a Dirac mass), lepton number
and electric charge would be violated.

P.S. Sorry for the quadruple post earlier.  My posting software was acting
up; I wasn't trying to prove my claims by repeated assertion!

--
Staccato signals of constant information,  |  -- David Brahm
A loose affiliation of millionaires and    |  (brahm@coil.caltech.edu)
  billionaires and Baby ...                |---------------------------
These are the days of miracle and wonder,  | Disclaimer:  I only speak
And don't cry, Baby, don't cry, don't cry. |   for the sensible folks.
Newsgroups: sci.physics
From: brahm@cco.caltech.edu (David E. Brahm)
Subject: Re: mass definition in particle physics
Summary: No theory predicts fermion masses
Organization: California Institute of Technology, Pasadena
Date: Tue, 14 Apr 1992 02:48:15 GMT

s5169180@deimos.ucc.umass.edu (S5169180) asks:
> [Can we] predict masses of quarks or leptons purely in theoretical way,
> instead of experiments?

No, there is no accepted theory of the fermion masses.  On the other hand
the gauge boson masses (W,Z) are predictable (M_W = gv/2), and their
detection at CERN with the predicted masses was a great triumph for the
Standard Model.  Of the Standard Model's 19 free parameters, most are
related to masses:
  9 quark and lepton masses (top mass still unknown)
  4 CKM matrix parameters (3 angles, 1 phase), related to quark masses
  2 Higgs parameters: vev is known, Higgs mass is unknown
  3 gauge couplings
  1 Theta_QCD = 0 but nobody's sure why

--
Staccato signals of constant information,  |  -- David Brahm
A loose affiliation of millionaires and    |  (brahm@coil.caltech.edu)
  billionaires and Baby ...                |---------------------------
These are the days of miracle and wonder,  | I will not post 4 copies
And don't cry, Baby, don't cry, don't cry. |   of the same article...
Newsgroups: sci.physics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Physics and Parapsychology: Reputation of Jack Sarfatti
Organization: Simon Fraser University
Date: Thu, 9 Apr 1992 21:18:19 GMT

In article <92100.083905J5J@psuvm.psu.edu> John A. Johnson <J5J@psuvm.psu.edu>
writes:
>As an undergraduate I read Bob Toben's _Space-Time and Beyond:
>Toward an Explanation of the Unexplainable_, which was partially
>based on conversations with physicists Jack Sarfatti and Fred Wolf.
>
>I am curious about how physicists whose ideas are used to support
>parapsychological ideas are regarded by the physics establishment.

I think you have not asked the question you thought you were asking.
I've heard Newton's, Einstein's, and Schroedinger's ideas all used
putatively "to support parapsychological ideas". All three are well
thought of by the "physics establishment" if I infer the intended
meaning of that phrase correctly as being "real physicists".

I think you meant to ask how we conservative physicists regard our
colleagues who argue in favor of acceptance of the substantiality of 
"parapsychological ideas". The answer is that when they argue by the
canons of science we think them responsible. When they cross the 
line and join the kooks, which can be done by invoking new science
created specifically for the purpose of supporting those ideas and
being otherwise without testable validity, we consider them to be 
kooks. 

The so-called "shyness effect" is just such a piece of ad hoc new 
science. It is the idea that phenomena can not be demonstrated to 
people who do not believe in them. Since I have had phenomena 
demonstrated to me in which I did not initially believe, and since I 
have demonstrated such phenomena to similarly sceptical colleagues, 
I can testify that the "shyness effect" does not seem to apply to at 
least a large range of physical phenomena, and I see no compelling 
reason to accept it in these other cases.

Leigh Palmer
establishment physicist
Newsgroups: sci.physics
From: srctran@world.std.com (Gregory Aharonian)
Subject: Why it is either religion OR science
Organization: The World
Distribution: sci.physics
Date: Wed, 15 Apr 1992 14:50:01 GMT

    A recent article in the New York Time reminded me why religion and
science have little in common and are not very compatible.
    The article described how the Catholic bishops in America have spent
nine years (yes nine years) trying to write a pastoral letter that condemns
sexism and says that women should be equal.  The reason for the delay is
that the more liberal Americans draft seemingly obvious statements about
women's rights that the conservatives in the Vatican strongly oppose.
    While it is amazing that these people can't accept that laws and rules
governing men and women should be invariant (except for the symmetry breaking
of childbirth), a statement in the article shows the vast gulf that exists
between the religious and scientific mind.
    In the article, Dr. Susan Muto, a professor at Duquesne University in
Pittsburgh, and a principal writer of the pastoral letter for the bishops,
comments on the very lengthy process to write a seemingly simple letter by
stating  "Who knows what the Holy Spirit will want from us 50 years from now,
but this seems as far as we can go now".
    God needs another 50 years to decide women have eqaul rights with men?
If Dr. Muto is serious, her statement illustrates how different the religious
and scientific mind is, and why you have to choose between them.  If Dr. Muto
is being sarcastic, her statement reflects the complaint that religion sticks
to outdated views of the world that eventually become silly.

    In fifty years, science will probably be on the verge of creating life
(by using self-replicating molecules that can process simple algorithms
discovered by the artificial life computer programmers).  Meanwhile, religious
people will still be trying to figure out if women are equal to men.  (and
four hundred yeas ago I would have been burnt to death for writing this
comment).

Gregory Aharonian
Newsgroups: sci.physics,sci.skeptic
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Question about dimmer switch and lamp.
Organization: Simon Fraser University
Date: Thu, 9 Apr 1992 21:29:42 GMT

In article <1992Apr8.155120.29611@EE.Stanford.EDU> siegman@EE.Stanford.EDU
(Anthony E. Siegman) writes:

>(I don't know the answer, but would hazard a guess that there's no
>true hysteresis in the bulb itself.)

I don't know the answer either, but I'd put money on that guess. Does
the dimmer you're using work by interrupting the current with an SCR
circuit of some kind? I know that I've got one of those in my house.
If you leave the dimmer set at a sub-threshhold level for a long time
does the light eventually come on, dimly? 

I have noted the same behaviour in some of my dimmers (but not all!)
and I will have to try that experiment. If the light eventually comes
on I can explain it easily (there's no hysteresis). Otherwise I'd bet
the hysteresis is inherent to either the controller alone or to it
and the non-ohmic lightbulb.

Leigh
From: phillips@FOZZIE.NRL.NAVY.MIL (Lee Phillips)
Newsgroups: sci.physics
Subject: Re: MD visualizations
Date: 14 Apr 92 16:26:55 GMT
Article-I.D.: fozzie.9204141626.AA27589
Followup-To: sci.physics

Can you get hold of a Macintosh II series machine?  If you can, I would
suggest a free program called MacAtoms, ideal for your purposes.  I use
it for just this.
Newsgroups: sci.physics
From: gilham@csl.sri.com (Fred Gilham)
Subject: Re: Question about dimmer switch and lamp.
Organization: Computer Science Lab, SRI International, Menlo Park, CA.
Date: Fri, 10 Apr 1992 21:22:19 GMT


`` Can someone versed in physics please explain this phenomenon?
Given an incandescent lamp with a dimmer switch. The lamp is on.  One
can then slowly turn the dimmer knob and reduce the light intensity
until the filament is just barely glowing.  If , however the lamp is
off, and one slowly turns the dimmer switch up, no matter how slow,
the light always comes on rather suddenly and much brighter than in
the reverse process.  Why is that so ?''

Here's my shot at it....

An alternating current dimmer uses a multi-layer semiconductor device
called a triac to control the brightness of the lamp.  It does this by
varying the `conduction angle' or percentage of the waveform of the
sine wave when it is conducting.  So if the triac conducts for half of
the waveform, you'll get something like half power.  Note that a triac
is either on or off, so that you don't waste power in resistive
elements.

The triac is triggered by driving current through its `gate.'  Once
triggered, the triac continues to stay on, regardless of the gate
current, until current no longer flows through the main terminals of
the triac (but this happens automatically with alternating current).
Usually this current is derived from a capacitor which charges through
a variable resistor.  Another semiconductor device, known as a
bilateral trigger (or something like that), is connected from the
junction of the resistor and the capacitor to the gate of the triac.
Once the capacitor charges up to a certain point, the bilateral
trigger `breaks over' and the capacitor gets discharged through the
path to ground going through the bilateral trigger and the triac's
gate, and the current flow triggers the triac.  The process gets
repeated 120 times a second for 60hz power.

I've built these, so I know the above description is correct.

My speculation of why the effect in question happens is as follows:

For a transistor or diode, there is a certain threshold of voltage
that must be applied to the junction being forward biased before
you'll get current to flow through that junction.  For silicon
devices, this threshold is .6 volts.  I assume that triacs also have
this junction threshold that must be overcome.  Since semiconductor
junctions also act as capacitors, I speculate that if the triac has
been conducting recently (e.g the past half-cycle), there will be some
residual charge on the gate junction that will lower the threshold for
it to fire.  If it hasn't been conducting, there will be no such
lowering of the threshold, and you'll need a higher voltage on the
gate before it fires.

I'm not certain that the above explanation is correct.  But it makes
sense to me.  You really want to ask an electrical engineer.
--
-Fred Gilham          gilham@csl.sri.com 
Newsgroups: sci.physics
From: middle@sccs.syr.edu (A. Middleton)
Subject: Re: job shortage(!)
Reply-To: middle@sccs.syr.edu (A. Middleton)
Organization: Syracuse Center for Computational Science/Dept of Phsyics, Syracuse Univ
Date: Thu, 9 Apr 92 11:05:40 EDT

In article <92094.115034U53272@uicvm.uic.edu>, sterrett j collins <U53272@uicvm.uic.edu> writes:
>In article <1992Mar20.105314.5938@newstand.syr.edu>, middle@sccs.syr.edu (A.
>Middleton) says:
>>I went to graduate school so that I could do research in physics.
>>Job == doing research.
>>
>>Alan
>If that is your aspiration, you should not be looking for an academic
>job.  You should be looking for a job at one of the labs, or in
>industry.  There are too many good researchers/bad teachers in academia
>already.  Now if you want to be a good researcher/good teacher that is
>another thing, but how much effort have you put into the latter
>qualification?
>                              sterrett j collins
>                              university of illinois at chicago

I look forward very much to teaching and, from my experience so far,
which I have taken every opportunity to expand, I feel I would be good
at it, thank you. Certainly I should be looking for an academic
job.

Alan Middleton
From: gilligan@bldrdoc.gov (Jonathan M. Gilligan)
Newsgroups: sci.physics
Subject: Re: terminal particle energy for accelerators
Keywords: n
Date: 17 Apr 92 01:50:20 GMT
Distribution: world,local
Organization: National Institute of Standards and Technology

In article <70425@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
[question about syncrhotron radiation limits on particle accelerators]
>
>|>Whatever the reason, is there any possibility that there exists
>|>a yet undiscovered trick around this so that one could have an SSC type
>|>acclerator (as far as particle energies are concerned) in a 1 meter box?
>|>Or is this impossible in principle, given the state of physics today.
>Well, you coudn't put a colliding ring w/ SSC type energies into a box
>with getting a great deal of radiation. So the competing effect you
>describe above would be imensely increased. You might think of doing a

This is not practical, but just for fun, suppose that the walls of the
beamline were made of some material that would form an extremely high-Q
cavity for the synchrotron radiation. Then there would be a lot of
radiation, but it would be stored in the volume of the ring. If you
could engineer the phases correctly, you could get acceleration out of
it (I'm not talking perpetual motion here --- just a case where the
acceleration from the radiation field balances the loss to particle
kinetic energy due to emitting radiation a la thermal equilibrium within a
black body) your losses now are only the absorptive losses in the walls
of the ring, but I'm assuming (ridiculously, to be sure) very high Q.

Of course, the high-Q cavity would have a narrow bandwidth compared to
the bandwidth of the emitted synchrotron radiation, but this would just
mean that the particle could not emit in certain parts of the spectrum
We already know that atoms will not radiate in below-cutoff cavities.
Kleppner and Hinds & Haroche have demonstrated this.

The problem is making a cavity with high-Q across the bandwidth of the
synchrotron radiation. There's no such thing that I know of.

---Jon

Disclaimer: The government probably disagrees with my opinions.
From: dandy@sys6626.bison.mb.ca (Daniel Mutch)
Newsgroups: sci.physics
Subject: Totally new Thereom
Date: 15 Apr 92 03:32:43 GMT
Organization: system 6626 BBS, Winnipeg MB


   This is a theory that may not be new but it was thought up by one of 
the local minds. It states, "If a perfect sphere of hard material (i.e.
diamond) Was placed on a perfect plane that of equally hard material that 
was parralell to the ground in a gravital enviroment, either the sphere 
or the plane would become imperfect.
  This statement is based on the theory that: A perfect sphere on a 
perfect plane has an infinitly small point of contact, therefore, the 
pressure on that point would be infinitly great, so either the plane or 
sphere or both would metamorphise to create a greater contact point thus 
making a shape imperfect. 
  Any feedback would be appreciated.

    |) /\ |\| |) \/
                 /  (dandy@6626.bison.mb.ca)
From: siproj@grayhawk.rent.com (D. R. Arthur)
Newsgroups: sci.physics
Subject: Re: Asimov
Date: 9 Apr 92 03:36:45 GMT
Organization: grayhawk; Des Moines, Iowa public access unix; 515/277-6753

In article <8047@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:
>I heard on the news that Isaac Asimov died today.  Obit in Tuesday NYTimes?
>
>--
>J. A. Carr                                    |  "The New Frontier of which I  
>jac@gw.scri.fsu.edu                           |  speak is not a set of promises
>Florida State University  B-186               |  -- it is a set of challenges."
>Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)

 His death sounded imminent from some correspondence Janet Asimov sent
 saying he was to ill to respond to what I had sent him.  That was early
 March, so it is sad that it took that long.  Which of his books on physics
 is considered  to be the best.


-- 
 /----------------------------/
 / Chronocide - Euthanasia    /   siproj@grayhawk.rent.com
 /             for boredom?   /   Is that European or African?
 /----------------------------/
From: pk03+@andrew.cmu.edu (Paul Karol)
Newsgroups: sci.physics
Subject: Re: Def'n of interaction?
Date: 8 Apr 92 14:27:56 GMT
Organization: Chemistry, Carnegie Mellon, Pittsburgh, PA

[I don't know how the text of the message disappeared...it was a request
for a (fairly) rigorous definition of "interaction".

A lousey definition:  Two substances  A and B can be said to interact if
at least one property (energy state e.g.) of at least one of them
changes when A and B are together compared to when they are not together.

Grazie di nuovo,

Paul J. Karol
from Padova, Italy via TELNET
From: jmgreen@pilot.njin.net (Jim Green)
Newsgroups: sci.physics
Subject: Re: What are your favorite textbooks?
Date: 7 Apr 92 19:00:02 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

Thank you all for your responses to my query re Thermo books.
It appears that the entire galaxy is using Kittel and Kroemer

I have two followup questions:
Does ANYBODY use Stowe "Intro to Stat Mech and Thermo"??????
Who is the publisher of Reif?  Appears to be out7 of print!

Thanks Folks