Abstract
A new detection method using magnetization generated at triggered radiative emission of neutrino pairs (RENP), $ |e \rangle \rightarrow | g \rangle + \gamma + \sum_{ij}\nu_i \bar{\nu}_j $ (atomic de-transition from state $|e \rangle $ to state $|g \rangle$ emitting sum of neutrino pairs $\sum_{ij}\nu_i\bar{\nu}_j$ accompanied by a photon $\gamma$), is investigated in order to determine unknown neutrino properties; absolute neutrino masses of $\nu_i$ and Majorana/Dirac distinction. Magnetization associated with RENP events has parity violating component intrinsic to weak interaction enforced by crystal field effect in solids, and greatly helps background rejection of quantum electrodynamic (QED) origin even when these backgrounds are amplified. In proposed experiments we prepare a coherently excited body of trivalent lanthanoid ions, Er$^{3+}$ (a best candidate ion so far found), doped in a transparent dielectric crystal. The magnetic moment $\mu \langle \vec{S}\cdot\vec{k} \rangle/k $ arising from generated electron spin $\vec{S}$ parallel to trigger photon direction $\vec{k}/k$ is parity odd, and is absent in QED processes. The generated magnetic field of order nano gauss is stored in crystals long after pair emission event till spin relaxation time. An improved calculation method of coherent rate and angular distribution of magnetization is developed in order to incorporate finite size effect of crystal target beyond the infinite size limit in previous calculations.
Highlights
Neutrino oscillation experiments, despite their remarkable discovery and measurement of finite neutrino mass and mixing in interactions, cannot determine remaining important neutrino properties and physical parameters; absolute neutrino masses and Majorana/Dirac distinction
The process we have considered for neutrino study is either radiative neutrino pair ννemission (RENP) jei → jgi þ γ þ ννstimulated by trigger laser, or Raman stimulated radiative neutrino pair emission [7] in atomic deexcitation between two states, jei → jgi
In the present work we shall restrict to cases of neutrino pair emission, in which two-photon excitation from the ground state to excited state jei is followed by triggered RENP: jgi þ γ1 þ γ2 → jei; jei → jgi þ γs þ νν
Summary
Despite their remarkable discovery and measurement of finite neutrino mass and mixing in interactions, cannot determine remaining important neutrino properties and physical parameters; absolute neutrino masses and Majorana/Dirac distinction. Moments parallel to the trigger photon direction generated at neutrino pair emission: the expectation value in the final state jfi in RENP, gμBhfjS⃗ · kjfi, where kis the unit vector along the signal photon momentum k⃗ and S⃗ is the electron spin operator to be multiplied by gμB, the g factor times Bohr magneton for magnetization This quantity is parity odd and time reversal (T) even. Matrix elements of spin hS⃗ i are usually of order unity, while those of velocity operator hv⃗ i are less than 10−3, interference terms are at least smaller by 10−3 than rate ∝ hS⃗ i2 of a parity even quantity We shall quantify this ratio for the lanthanoid ion we use as a target. We use the natural unit of ħ 1⁄4 c 1⁄4 1 throughout the present work unless otherwise stated
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