SEARCH FOR THE DOUBLE BETA DECAY OF Nd 5 USING A MAGNETIC SPECTROMETER­DETECTOR Abstract by GARY R. SMITH A large aperture, low resolution magnetic ' spectrometer­detector was designed and constructed to search for the double "beta decay of Nd . The most sensitive probe for the Majorana nature of neutrinos is an extremely rare nuclear decay process called neutrinoless double beta decay ($$0\nu \beta \beta$$), where a nucleus with mass number A and charge Z decays by emitting only two electrons and changes its charge by two units (A,Z)$$\longrightarrow$$(A,Z+2) + 2e$$^{-}$$. Backgrounds recognized in previous experiments were suppressed to well below the observed event rate, and no other significant backgrounds are apparent. happens when a single beta decay cannot happen because the would-be daughter Z+1 nucleus has a higher energy than the original Z nucleus, but the Z+2 daughter has a lower energy. 5.1 Double beta decay (2 2 ) Some nuclei can only decay trough double beta decay, which was proposed by Maria Goeppert Mayer in 1935. The decay is rare, but becomes relevant due to the large amount of Xe-136 in the detector and the relative smallness of other background contributions. Models with scalars carrying lepton number − 2-2 − 2 are proposed for this purpose so that ordinary neutrinoless double beta decay is forbidden, and we can raise the scale of global symmetry breaking above the 10 keV scale needed for observable emission of conventional Majorons in double beta decay. The experiment was located at Laboratori Nazionali del Gran Sasso and ran for a period of about 5 years, from 2003 to 2008. [1,2,3] for recent reviews) is a rare nuclear process hypothesized to occur if neutrinos are Majorana particles. double beta result of [1–4], by further discussion of the structure of the experimental background, by statistical considerations and by analysis of other double beta experiments investigating the decay of 76Ge. In fact, the search for 0νββ is currently the only experimentally feasible method to establish the Majorana nature of the neutrino. The literature distinguishes between two types of double beta decay… All rights reserved. Double beta decay is a rare nuclear process changing the nuclear charge by two units leaving atomic number unchanged. In this letter, we argue that double-decay experiments could be used to probe models with light exotic fermions through the search for spectral distortions in In experiments, we measure the energies of the two emitting electrons. The observation of neutrinoless double beta decay (DBD) will have important consequences. The key scales of mee, which will lead to the discrimination among various schemes are: mee ∼ 0.1 eV and mee ∼ 0.005 eV. The spectro­ s­ meter­detector was operated for $at the level of (0.01--0.1) eV are considered. (a) -decay spectrum close to end-point. In a typical double beta decay, two neutrons in the nucleus are converted to protons, and two electrons and two electron antineutrinos are emitted. 1 Introduction The goal of the search for neutrinoless double beta decay (0νββ decay) is to establish the It is a slow process with very long half-lives because whatever happens in the nucleus that allows it to happen is very unlikely. In this work, we show that such strong$\ensuremath{\nu}\mathrm{SI}\$ can cause significant effects in two-neutrino double beta decay, leading to an observable enhancement of decay rates and to spectrum distortions. NEXT offers excellent performance in both aspects: an energy resolution of at least 1% FWHM at Qββ and a topological signature that provides an extra handle in background rejection. On one hand, a higher energy resolution excludes more events with energies close to … The Standard Model of Particle Physics predicts the double-decay of certain nuclei with the emission of two active neutrinos. There is an experiment to verify the existence of double beta decay, but I … No candidate events for the zero-neutrino double beta decay during 21 924 h results in a half-life limit of 2.7×1022 years at the 68% confidence level. Beta Decay 2 with the Tables for the Analysis of Beta Spectra produced by the National Bureau of Standards. As a result of this transformation, the nucleus emits two detectable beta particles, which are electrons or positrons. One such rare process is the yet-to-be-observed neutrinoless double beta decay. NEXT (Neutrino Experiment with a Xenon TPC) is a neutrinoless double-beta decay experiment that operates at the Canfranc Underground Laboratory (LSC). IntroductionNeutrinoless double-beta decay (0νββ) (see Refs. The two-neutrino double beta decay of Se82 has been measured during a 20 244 h run resulting in a half-life of 1.08−0.06+0.26×1020 years (68% C.L.). Understanding and mitigating background radiation is especially important in searches for very rare nuclear processes, which utilize sensitive detectors. Two-neutrino double-beta decay 2 − − is allowed in 2nd order even if single-beta decay is forbidden or suppressed: X +2 Y+2 −+2 FcosC CUORE searches for the characteristic signal of neutrinoless double beta decay, a small peak in the observed energy spectrum around the known decay energy; for 130 Te, this is Q = 2527.518 ± 0.013 keV. The role 0νββ decay searches will play in the reconstruction of the neutrino mass spectrum is clariﬁed. (b) 2 2 and 0 2 spectrum. The ββ0ν signal is a peak at the endpoint of the ββ2ν energy spectrum (Qββ). They are included in liquid Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND) Collaboration. This exotic process was first discussed in 1935 and after that it took 50 years until its first observation in 1987, where the 2νβ - β - decay of the isotope 82 Se was measured. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): We study the discovery potential of future beta decay experiments on searches for the neutrino mass in the sub-eV range, and, in particular, KATRIN experiment with sensitivity m> 0.3 eV. Within the limited statistics of the small data sample, the observed single-electron energy spectrum, … It only(?) If neutrinos are their own antiparticles, i.e., Majorana particles, NLDBD process can happen. double beta decay and other rare processes, including double beta decay with two neutrinos (2 ). Calculations of double beta decay nuclear matrix elements ･q. They are included in liquid 9.115B, … Why choosing xenon? If N(p)is the probability that an electron is emitted with momentum betweenp and p+dp, then, if the neutrino is massless we have: N(p)=CF(Z,p)p2(E 0 − E e)2 where C is a collection of constants. On one hand, a higher energy resolution excludes more events with energies close to (but different from) Qββ. Pairs of negative beta particles have been observed originating from a 82 Se source during a cloud-chamber search for double beta decay. The detection of the neutrino accompanied mode (A,Z)? The relations between the effective Majorana mass of the electron neutrino m ee responsible for neutrinoless double beta decay and the neutrino oscillation parameters are considered. On one hand, a higher energy resolution excludes more events with energies close to (but different from) Q ββ. The results of the most sensitive experiments are discussed. process of two neutrino double beta (2νββ) decay is exper- imentally observed in 11 out of 35 possible DBD nuclides [1,2], the lepton number violating process of zero neutrino double beta (0νββ) decay remains elusive to date. Extensions of the Standard Model . double beta result of [1–4], by further discussion of the structure of the experimental background, by statistical considerations and by analysis of other double beta experiments investigating the decay of 76Ge. Beta Decay 2 with the Tables for the Analysis of Beta Spectra produced by the National Bureau of Standards. In 1900, Paul Villardide… We show that for any specific oscillation pattern m ee can take any value (from zero to the existing upper bound) for normal mass hierarchy and it can have a minimum for inverse hierarchy. Important points in the analysis of the measured spectrum are … Double beta decay is a rare nuclear process changing the nuclear charge by two units leaving atomic number unchanged. The process can be thought as two simultaneous beta minus decays. In 1899, Ernest Rutherford separated radioactive emissions into two types: alpha and beta (now beta minus), based on penetration of objects and ability to cause ionization. Neutrinoless Double Beta Decay ... 2νββ is clearly observed, and the peak spectrum of 136Xe 0νββ decay is contaminated by backgrounds. Neutrinoless Double Beta Decay ... 2νββ is clearly observed, and the peak spectrum of 136Xe 0νββ decay is contaminated by backgrounds. The present status of double beta decay experiments is reviewed. 40K is also contained in liquid scintillator. Neutrinoless double-beta decay is a forbidden, lepton-number-violating nuclear transition whose observation would have fundamental implications for neutrino physics, theories beyond the Standard Model, and cosmology. In neutrinoless double beta decay searches, two ingredients have crucial importance: energy resolution and background suppression. Xe-136 is also responsible for the second gray-shaded region at high energies which might contain an experimental signature of its neutrinoless double -decay. On the other hand, due to the large half-life of the searched decay, an optimal background identification is mandatory in order to reject events whose energy falls inside the energy window, to the greatest extent possible. The ββ0ν signal is a peak at the endpoint of the ββ2ν energy spectrum (Q ββ). Double Beta Decay NRC Review, Dec. 2010 The major physics questions addressed by ββββββ • Decay can only occur if neutrinos are massive Majorana particles • This conclusion is model independent if ββ is observed. The 2νββ decay would produce a broad peak covering a wide range of energies, as this peak represents a broad spectrum of energies that the two β-particles share with two neutrinos (i.e., four particles share the 2813.49 keV decay energy, two β-particles and two neutrinos); whereas, the neutrinoless double beta decay (0νββ) would be manifested as a single peak at 2813.49 keV, as illustrated in Fig. Neutrinoless double-beta decay is a forbidden, lepton-number-violating nuclear transition whose observation would have fundamental implications for neutrino physics, theories beyond the Standard Model, and cosmology. My question is does this reaction in beta decay result in the existence of the beta spectrum? In neutrinoless double beta decay searches, two ingredients have crucial importance: energy resolution and background suppression. In this review, we summarize the theoretical progress to understand this process, the expectations and implications under various particle physics models, and the nuclear physics … The standard double-beta decay process (2νββ) has been observed in a handful of nuclei, and occurs when a parent nucleus decays to a daugher nucleus via: (A, Z) → (A, Z + 2) + 2e - + 2ν̅ e In 0νββ, which is forbidden in the standard model, no neutrinos are emitted and the lepton number is violated by two units: If N(p)is the probability that an electron is emitted with momentum betweenp and p+dp, then, if the neutrino is massless we have: N(p)=CF(Z,p)p2(E 0 − E e)2 where C is a collection of constants. Currently a limit for the electron neutrino mass of less than 2.2 eV has been achieved [10]. Calculations of double beta decay nuclear matrix elements ･q. Important points in the analysis of the measured spectrum are … In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. A similar limit is The former has been awarded an Advanced Grant of the European Research Council for NEXT in 2013 and the latter received the American Physical Society’s inaugural “Particles and Fields Instrumentation Award” in 2015, for his invention in the 1970s of the Time Project Chamber. Copyright © 2011 NEXT Collaboration. The goal of the search for neutrinoless double beta decay (0νββ decay) is to establish the violation of (total) lepton number L and to measure the Majorana mass of the electron neutrino, thus identifying the nature of the neutrino [1, 2]. 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