Re: Dangerous Ion Colliding Experiment? (Long - includes theory o f the field)

[Samuel Held <Held@RHIP.PHYS.UTK.EDU>]

Ludwik,
        There is an expansion.  Also, the original collision region does
have an initial size bigger than the size of the nuclei.  It is a very
complex situation.  If you look at the literature, there is work with
hydrodynamical models to try to model this very complex system.  Your
math is correct, there is   ~40 TeV available.  Another point I failed
to mention is that equation for R is only an approximation that works
for small A atoms.  I will try to find out more, but let me say that the
estimates range from 2-6 GeV/fm^3 (lattice QCD predicts the 2-3 range).
The order of magnitude is correct.  Sorry I can't give you a better
answer, but I only ever got a hand waving answer myself.  This makes me
want to find out.  I will e-mail you tomorrow or Monday with a response.



Sam Held


-----Original Message-----
From: Ludwik Kowalski [mailto:KowalskiL@MAIL.MONTCLAIR.EDU]
Sent: Saturday, July 24, 1999 2:14 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: Dangerous Ion Colliding Experiment? (Long - includes theory
o fthefield)


Hi Sam:
Last night, referring to

> > ... This translates roughly into 2-3 GeV [per cubic Fermi] which
> > we believe is roughly high enough to trigger the"phase transition"
> > into deconfined [quark-gluon] matter.

I asked:

> What is the basis of your belief? How confident
> are you about the order of magnitude?

Let me ask an easier question about your valuable contribution.

You wrote:

> The largest system we will be colliding will be Au nuclei.  So
> you can use the R = 1.2 fm (A)^1/3 to find the size of the system
> (1 fm = 10^-15 m).  It is very high density and subsequent high
> temperatures in very, very small volumes for very,, very short amounts
> of time.  The quark-gluon plasma is predicted to live for only 10^-23 s

> so we will only see the aftermath.  One of which is increased strange
> matter production but I will get to that below.  The temperature of the

> matter for the 10^-23 s will be very high.  We will have in the center
> of mass (or momentum) frame an energy of 100 GeV for every nucleon
> (2 x197).  One Kelvin is 1/40 eV, so the conversion is 1 trillion
Kelvins
> or 1 x 10^12 K (if my math is right).  This translates roughly into 2-3
GeV
> per cubic fermi (fm) which we believe is roughly high enough to trigger

> the "phase transition" into deconfined matter.

Reading this again I am not able to consolidate 100 GeV/nucleon
with 2-3 GeV per cubic fermi. (The volume of 2*197 nucleons,
under ordinary conditions, would be 2852 cubic fermis. The
combined injected energy  is 100*2*197 =394000 GeV. This
would give 138 GeV per cubic fermi, about 50 times more than
what you show. My number would tend to be larger, not smaller,
if a compression of nuclear matter were allowed.)

What am I missing? Some kind of expansion rather than
compression? Or just a trivial error somewhere?

Ludwik Kowalski