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Specific heat of a heavy ion plasma

  1. Dec 15, 2011 #1
    I am surprised by the result when I estimate the specific heat of the plasma produced by heavy ion collisions in the LHC:
    C(plasma) ~= 2e5 J/(g-K) (Details below.)
    This is ~1e6 times greater than C(lead)=0.13 J/(g-K) (1).
    Did I make a mistake? If not, can the physics experts who read this explain why the specific heat is so high? (Extra degrees of freedom, ...?)

    Thanks in advance for your feedback.
    Estimate of specific heat of a heavy ion plasma at LHC:
    C = energy added/(mass*change in temperature)

    Energy added:
    Energy of a heavy-ion collison at LHC = 1150 TeV (2).
    Energy = 1150 TeV * 1.6e-7 J/TeV = 1.8e-4 J

    I assume plasma is made of 2 lead nuclei which collide.
    Mass = 2 x 206 nuceons x 1.66e-24 g/nucleon = 6.8e-22 g

    Heavy ion plasma temp at LHC exceeds 100,000 X solar core temp (3).
    Temp>=1.6e7 K *1e5 = 1.6e12 K

    C = energy added/(mass*change in temperature)
    C = 1.7e5 J/(g-K)

    (1) http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html
    (2) http://cdsweb.cern.ch/record/1165534/files/CERN-Brochure-2009-003-Eng.pdf, p.21.
    (3) Ibid., p.25.
  2. jcsd
  3. Dec 15, 2011 #2

    Vanadium 50

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    There are many, many more degrees of freedom than just two lead nuclei. Indeed, one can argue the point of the experiment is to measure them. One finds there are more than you would expect even from just 208+208 participating nucleons.
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