The Jagiellonian PET (J-PET) experiment aims at performing a test of the symmetry under reversal in time in a purely leptonic system constituted by
orthopositronium (o-Ps) with a precision unprecedented in this sector.
It should be noted in this regard that the shape of the shoulder is influenced by the
orthopositronium (o - Ps, [sup.T]Ps) component of the lifetime spectrum ([I.sub.2]), following the component of annihilation of quasi-free positrons ([e.sup.+.sub.[beta]]) on the time axis.
A small contribution coming to [[tau].sub.1] from parapositronium atoms of lifetime 125 ps is ignored as the intensity of this component, one-third that of the
orthopositronium intensity 73, is negligibly small.
The pick-off lifetime of
orthopositronium, o-Ps, is correlated to the free volume hole size in polymers (6).
If the spin of the positron and the spin of the electron point in the same direction, the material is known as
orthopositronium. Unlike a stable hydrogen atom,
orthopositronium lasts only for about 140 nanoseconds, before its components annihilate each other in a burst of pure energy.
A proposed experiment is connected to
orthopositronium annihilation anomalies, which, being related to one of known unmatter entity,
orthopositronium (built on electron and positron), opens a way to expand the Standard Model.
If the frequency of the density fluctuation is slower than the positron or
orthoPositronium (oPs) annihilation frequency ([similar to][10.sup.10] [s.sup.-1]), then the positron effectively "sees" the free volume, both dynamic and static, and can detect molecular relaxations.
This explains why
orthopositronium, where the particle (electron and positron) spins are parallel and hence the magnetic component of the electromagnetic interaction is repulsive, has a higher energy state than parapositronium where the particle spins are anti-parallel and the magnetic component of QED is attractive.
By the mentioned new QED effect and by the new formulation of the BS equation, a term in the
orthopositronium decay rate that is missing in the conventional QED is found, resolving the
orthopositronium lifetime puzzle completely.
On the possibility of nuclear synthesis during
orthopositronium formation.
Observations of the "isotopic anomaly" of positron ([sup.22]Na) annihilation lifetime spectra in samples of gaseous neon of various isotopic abundance, the independent observations of the
orthopositronium lifetime anomaly, and comparison of unique experimental data on the positron's annihilation lifetime spectra in condensed deuterium ([D.sub.2]) and protium ([H.sub.2]), suggest a hypothesis on synthesis of [sup.4]He during the
orthopositronium formation in deuterium.
This letter gives a history of two observed anomalies of
orthopositronium annihilation, of which the 20th anniversary occurs this year.