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01/14/09P.A.Ganai - NIT SRINAGAR

Prince Ahmad GanaiPrince Ahmad GanaiDepartment of Physics NIT SrinagarDepartment of Physics NIT Srinagar

prince_ganai.blogspot.comprince_ganai.blogspot.comprince_ganai@[email protected]

Understanding a nuclear system


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Introduction Protons and their decay Neutrons and their decay Nuclear system

Binding energy Fusion and Fission Experimental facilities LHC

Theoretical Challenges Summary


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Contributor


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One of the implications of the grand unification theories is that theproton should decay with a half-life on the order of 1032 years. Such along half-life is exceedingly difficult to measure, but the hope of doingled to a deep mine experiment in the Soudan iron mines of Minnesota.The Soudan 2 Proton Decay experiment ran from 1989-2001 withoutobserving any convincing proton decays. Such experiments serve topush back the lower bound on the proton decay half life.

Another set of experiments designed to detect proton decay wascarried out in the water Cherenkov detector at Super KamiokandeinJapan. Ed Kearns of Boston University suggested the followingtentative bounds for proton decay in a review in 2001.

Proton


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The decay of the neutron is associated with a quarktransformation in which a down quark is converted to an up

by the weak interaction . The average lifetime of 10.3 min/0.693= 14.9 minutes is surprisingly long for a particle decay thatyields 1.29 MeV of energy. You could say that this decay issteeply "downhill" in energy and would be expected toproceed rapidly. It is possible for a proton to be transformedinto a neutron, but you have to supply 1.29 MeV of energy toreach the threshold for that transformation. In the very early

stages of the big bang when the thermal energy was muchreater than 1.29 MeV we surmise that the transformation

Neutron
http://hyperphysics.phy-astr.gsu.edu/HBASE/astro/bbcloc.html#c1http://hyperphysics.phy-astr.gsu.edu/HBASE/astro/bbcloc.html#c1


7/3001/14/09P.A.Ganai - NIT SRINAGAR

Decay of the Neutron

A free neutron will decay with a half-life ofabout 10.3 minutes but it is stable ifcombined into a nucleus. This decay is anexample of beta decay with the emission ofan electron and an electron antineutrino.The decay of the neutron involves theweak interaction as indicated in the

A more detailed diagram of the neutron'sdecay identifies it as the transformation ofone of the neutron's down quarks into anup quark. It is an example of the kind ofquark transformations that are involved in

many nuclear processes, including beta



Summary of Masses


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100meters

Nucleus

1mm

Electrons

Atom Mostly empty

Electric Force



Nuclear



Nuclei are made up of protons and neutron, but themass of a nucleus is always less than the sum of theindividual masses of the protons and neutronswhich constitute it. The difference is a measure ofthe nuclear binding energy which holds the nucleustogether. This binding energy can be calculated fromthe Einstein relationship:

Nuclear binding energy = mc2

For the alpha particle m= 0.0304 u which gives abinding energy of 28.3 MeV.

Nuclear Binding Energy



The enormity of the nuclear binding energy canperhaps be better appreciated by comparing it to thebinding energy of an electron in an atom. Thecomparison of the alpha particle binding energywith the binding energy of the electron in ahydrogen atom is shown below. The nuclear binding

energies are on the order of a million times greaterthan the electron binding energies of atoms.

comparis



Fission and fusion can yield energy



Nuclear


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Nuclear


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Radio activityRadio activity


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The Large Hadron

The Large Hadron Collider (LHC) is agigantic scientific instrument nearGeneva, where it spans the borderbetween Switzerland and Franceabout 100 m underground. It is aparticle accelerator used byphysicists to study the smallest

known particles the fundamentalbuilding blocks of all things. It willrevolutionise our understanding, fromthe minuscule world deep within


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Beam


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Detecto


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NSC


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I


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Collective Models Shell Structure No- Core Models

HFB PHFB FTHFB Monticarlo calculations

Nuclear TheoryNuclear Theory


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vFinally I would like you to thinkthat if protons were unstable, bythat I mean that their decaytime is from few minutes to fewyears, then would we exist tosolve the mysteries of nature ?.

vThe nature cant be thataccidental, that every law is in

ThankxThankx

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