Neutrino heating

Neutrino Temperature Assuming the neutrino spectrum to be Fermi-Dirac distribution with the vanishing chemical potential, we got the Fe temperature, T [3,4]. For the Kamiokande data, T is 2.6 3.lMeV, for IMB 3.9 5.3 MeV. These values are a little close to the values by those who insist the late time neutrino heating mechanism of the explosion. 

It is generally accepted that the r-process synthesis of the heavy neutron capture elements in the mass regime A S 130-140 occurs in an environment associated with massive stars. This results from two factors (i) the two most promising mechanisms for r-process synthesis—a neutrino heated hot bubble and neutron star mergers— are both tied to environments associated with core collapse supernovae and (ii) observations of old stars (discussed in Section 1.01.6) confirm the early entry of r-process isotopes into galactic matter. 

Fig. 10. Simulation of an electron-capture supernova following the collapse of an O-Ne core. The time evolution of the radius of various mass shells is displayed with the inner boundaries of the O+Ne, C+O and He shells marked by thick lines. The inner core of about 0.8 M is mainly made of Ne at the onset of collapse ([21], and references therein). The explosion is driven by the baryonic wind caused by neutrino heating around the PNS. The thick solid, dashed, and dash-dotted lines mark the neutrino spheres of ve, ve, and heavy-lepton neutrinos, respectively. The thin dashed line indicates the gain radius which separates the layers cooled from those heated by the neutrino flow. The thick line starting at t = 0 is the outward moving supernova shock (from [22])...

The effect of thermal pion fluctuations on the specific heat and the neutrino emissivity of neutron stars was discussed in [27, 28] together with other in-medium effects, see also reviews [29, 30], Neutron pair breaking and formation (PBF) neutrino process on the neutral current was studied in [31, 32] for the hadron matter. Also ref. [32] added the proton PBF process in the hadron matter and correlation processes, and ref. [33] included quark PBF processes in quark matter. PBF processes were studied by two different methods with the help of Bogolubov transformation for the fermion wave function [31, 33] and within Schwinger-Kadanoff-Baym-Keldysh formalism for nonequilibrium normal and anomalous fermion Green functions [32, 28, 29],... 

The lion s share of fluorine is produced by the intense burst of neutrinos that occurs when the Type II supernova core collapses. Although neutrinos interact only infrequently with matter, a tiny fraction of their intense flux during a 10-second burst drives a proton or neutron from the 20Ne nucleus, in either case resulting in 19F. This occurs where both 20Ne and the neutrino flux are most abundant, near the core of the exploding massive star. Much of this 19F is subsequently destroyed by nuclear reactions in the heated gas when the shock wave passes, but enough survives to account for the 19F/2°Ne abundance ratio in the Sun. 

Type II supernovae are massive stars, ones that progress in their nuclear fuels well past the fusion of carbon and the fusion of oxygen at their centers. When their cores run out of nuclear fuel, those central regions collapse to form a neutron star, or in some cases a black hole. The incredibly intense emission of neutrinos from the newly born neutron star so heats the overlying layers, aided by an outward moving shock wave of pressure, that those layers pardy explode and are ejected. The last of these thatwas visible to the naked eye occurred in 1987, and demonstrated for the first time the correctness of the intense neutrino burst that is their main energy output. 

The bounce shock heats up deleptonized matter and rapidly spends most of its kinetic energy to destroy nuclei and produce plenty of free nucleons (n, p). Modified URCA-processes [38] becomes important e + p n + ve, e++n —> p+ue and pair-neutrino annihilation takes place e++e — ve IL-At the typical collapse temperatures T 10 MeV a lot of z/s is produced [168] However, at densities p 1012 g/cm3 the mean free path of 10 MeV neutrinos is by 5-6 orders of magnitude smaller than the size of the proto neutron star (R 50 km) so the opaque neutrinosphere forms. Most of the core collapse neutrinos diffuse out of the neutrinosphere on a time scale 10 seconds. First calculations of v spectra in core collapse SN were performed by D.K. Nadyozhin [108, 109] We should note that subsequent detailed calculations (e.g. [101] and references therein) did not change much these spectra. Thus, the modest 10% fraction of the total neutrino energy released in the core collapse ( 1053 ergs) would be sufficient to unbind the overlying stellar envelope and produce the phenomenon of type II supernova explosion. 

As the universe expands and cools below the electron rest mass energy, the e pairs annihilate, heating the CMB photons, but not the neutrinos which have already decoupled. The decoupled neutrinos continue to cool by the expansion of the universe (T oc a-1), as do the photons which now have a higher temperature T1 = (11 /4)4/3T (n7/n = 11/3). During these epochs... 

In the latter case, we also need to know how much of the energy is available for heating the stellar material (photons, electrons, positrons) and how much is lost in the form of neutrinos. 

The isomeric gamma rays occur 5 x 10 to 10 seconds after fission. All but the anti-neutrinos provide sensible heat. The total energy emission per fission Is seen to be 204.3 + 2.5 Mev vlth 194.O Mev of it appearing as sensible beat in the reactor. The se condary lanergy sources m the reactor are those associated vlth various neutron interactions. These energy sources are given in Table 9.1.2. specific energies depend on the reactor. 

It was scientists who exposed the false findings behind the cold fusion case in 1989, when a pair of researchers (Martin Fleischmann and Stanley Pons) publicly claimed (mistakenly) that they had produced fusion and heat production during the electrolysis of heavy water it was careful and persistent application of scientific methodology that identified the errors in the claim from CERN that neutrinos were superluminal and could travel faster than light. 

H at of Fission - The energy released by the fission process and which can be converted to heat. This specifically excludes the neutrino energy. The value given in Glasstone and Sdlund is I9I Mev/fission. This means that about 3 x 10 0 fissions/sec. will produce a pile power of one watt. 

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