Beta Beam Research Articles

Exploration prospects of a long baseline beta beam neutrino experiment with an iron calorimeter detector

A high intensity source of a single neutrino flavour with known spectrum is most desirable for precision measurements, the consensus direction for the future. The beta beam is an especially suitable option for this. We discuss the prospects of a very long baseline beta beam experiment with a magnetized iron calorimeter detector. In particular, with the source at CERN and the detector at the proposed India-based Neutrino Observatory (INO) the baseline is near the ‘magic’ value where the effect of the CP phase is small. We observe that this experiment will be well suited to determine the sign of m32−m22 and will be capable of probing θ13 down to about 1°.

Higher γ's and smaller detectors for the Beta Beam

The Beta Beam concept is a very promising technology to achieve high intensity and high purity neutrino beams. The main limitation of the Beta Beam in its baseline configuration (“low-γ option”) resides in the smallness of the parent ion energy. Here, the emerging electron neutrinos have an energy of a few hundreds MeV, i.e. a spectrum that significantly limits the physics reach of the facility. Moreover, in order to attain sensitivities comparable to a Phase II Superbeam, the construction of a Mton size detector is mandatory to overcome the smallness of the cross sections. In the following, we discuss a few recent proposals for an increase of the parent ion energy (“high-γ options”) with emphasis on physics performances and technological challenges.

Optimal Staging of Acceleration and Cooling in a Neutrino Factory

Schemes to produce intense sources of high-energy muons, Neutrino Factories, beta beams, and colliders, require collection, rf capture, and transport of particle beams with unprecedented emittances, both longitudinally and transversely. These large initial emittances must be reduced or cooled both in size and in energy spread before the muons can be efficiently accelerated to multi-GeV energies. The acceleration stage becomes critical in formulating and optimizing muon beams; individual stages are strongly interlinked and not independent as is the case in most conventional acceleration systems. Most importantly, the degree of cooling, or cooling channel, depends on the choice of acceleration. This work discusses two basic, but different approaches to a Neutrino Factory and how the optimal strategy depends on beam parameters and method of acceleration.

Summary and Conclusions from the Neutrino Factory and Beta Beams Group, APS Multi-Divisional Study of the Physics of Neutrinos

Conclusions from the Neutrino Factory and Beta Beam Working Group within the recent APS sponsored Neutrino Physics Study are summarized.

SPL and Beta Beams to the Frejus

Physics potential of a conventional neutrino beam generated by the 2.2 GeV, 4MW, Superconducting Proton Linac and of a Beta Beam fired to a gigantic water Cerenkov detector hosted below Frejus, 130 km away from CERN, are briefly summarized. θ13 sensitivity could be improved by up to 3 orders of magnitude with respect to the present experimental limit and a first sensitive search for leptonic CP violation could be performed.

Beta Beams

Beta Beams could address the needs of long term neutrino oscillation experiments. They can produce extremely pure neutrino beams through the decays of relativistic radioactive ions. The baseline scenario is described, together with its physics performances. Using a megaton water Cerenkov detector installed under the Frejus, Beta Beams could improve by a factor 200 the present limits on $\sin^2{2 \thetaot}$ and discover leptonic CP violating effects if the CP phase delta would be greater than 30 degree and theta13 greater than 1 degree. These performances can be further improved if a neutrino SuperBeam generated by the SPL 4MW, 2.2 GeV, proton Linac would be fired to the same detector. Innovative ideas on higher and lower energy Beta Beams are also described.

High energy beta beams without massive detectors

In this paper, the possibility to exploit a high energy beta beam without massive detectors is discussed. The radioactive ions are boosted up to very high $\gamma$ with the neutrino beam pointing towards an instrumented surface located at a moderate baseline (e.g. from CERN to the Gran Sasso Laboratories). $\nu_e \to \nu_\mu$ oscillations and their CP conjugate are tagged as an excess of horizontal muons produced in the rock and tracked by the low-mass instrumented surface installed in one of the LNGS experimental halls. We show that the performance of this complex for what concerns the determination of the $\theta_{13}$ angle of the leptonic mixing matrix is comparable with the current low-$\gamma$ design based on a gigantic water Cherenkov at Frejus.

Neutrino-lead cross section measurements using stopped pions and low energyβbeams

Two new facilities have recently been proposed to measure low energy neutrino-nucleus cross sections, the nu-SNS (Spallation Neutron Source) and low energy beta beams. The former produces neutrinos by pion decay at rest, while the latter produces neutrinos from the beta decays of accelerated ions. One of the uses of neutrino-nucleus cross section measurements is for supernova studies, where typical neutrino energies are 10s of MeV. In this energy range there are many different components to the nuclear response and this makes the theoretical interpretation of the results of such an experiment complex. Although even one measurement on a heavy nucleus such as lead is much anticipated, more than one data set would be still better. We suggest that this can be done by breaking the electron spectrum down into the parts produced in coincidence with one or two neutrons, running a beta beam at more than one energy, comparing the spectra produced with pions and a beta beam or any combination of these.

Physics reach of the beta beam

Beta beams are designed to produce pure (anti)electron neutrino beams and could be an elegant and powerful option for the search of leptonic CP violating processes. In this paper will be quantified the physics reach of a CERN based beta beam and of a super beam–beta beam combination. The CP phase δ sensitivity results to be comparable to a neutrino factory for sin2θ13 values greater than 10−4.

Physics potential of the SPL super beam

Beta beams are designed to produce pure (anti)electron neutrino beams and could be an elegant and powerful option for the search of leptonic CP violating processes. In this paper will be quantified the physics reach of a CERN based beta beam and of a super beam–beta beam combination. The CP phase δ sensitivity results to be comparable to a neutrino factory for sin2θ13 values greater than 10−4.

Comparison of electron beam irradiation with gamma processing for medical packaging materials

Ionizing radiation is known to degrade materials and in the meantime is capable of novel property creation. In the medical device industry, sterilization by ionizing radiation has become increasingly popular. In particular, the beta or electron beam irradiation has been adopted along with the traditional gamma radiation from Cobalt or Cesium sources. Of course, the ionizing radiation which disrupts bio-macromolecular structures in bio-burdens can damage polymer chains. Although the mode of radiation interaction is similar, gamma and high-energy electrons differ in several subtle ways: dose rate, sample temperature rise, oxygen availability and treatment duration. We have conducted a comparative study on material interactions due to e-beam irradiation and treatment with gamma. A similarity between the two processes as well as significant differences will be presented.

Excitation of high frequency pressure driven modes in non-axisymmetric equilibrium at high βpol in PBX-M

High frequency pressure driven modes have been observed in high poloidal beta discharges in the Princeton Beta Experiment Modification (PBX-M). These modes are excited in a non-axisymmetric equilibrium characterized by a large, low frequency mt = 1/nt = 1 island, and they are capable of expelling fast ions. The modes reside on or very close to the q = 1 surface and have mode numbers with either mh = nh or (less probably) mh/nh = mh/(mh-1), with mh varying between 3 and 10. Occasionally these modes are simultaneously localized in the vicinity of the ml = 2/nl = 1 island. The high frequency modes near the q = 1 surface also exhibit a ballooning character, being significantly stronger on the large major radius side of the plasma. When a large mt = 1/nt = 1 island is present, the mode is poloidally localized in the immediate vicinity of the X point of the island. The modes occur exclusively in high beta beam heated discharges and are likely to be driven by the beam ions. They can thus be a manifestation of either a toroidicity induced shear Alfven eigenmode (TAE) at q = (2mh+1)/2nh, a kinetic ballooning mode, or some other type of pressure driven (high β) mode. Most of the data are consistent with the theoretical predictions for the TAE gap mode. Since the high frequency modes in PBX-M, however, are found exclusively on or in the immediate neighbourhood of magnetic surfaces with low rational numbers (q = 1, 2,...), other possibilities are not excluded

Electromagnetic instabilities driven by unequal proton beams in the solar wind

The paper sets forth a numerical investigation of the linear dispersion relation for typical solar wind conditions at 1 AU during those times (high-speed streams) when a secondary beam of protons drifting relative to the main proton component is present. Three beam-driven instabilities were found to occur as the beam drift velocity approaches the Alfven speed: (1) a pure, field-aligned magnetosonic wave that is most important at relatively high beta and/or high beam drift speeds; (2) an oblique magnetosonic wave having highest growth rates 15-30 deg from the magnetic field; and (3) an oblique Alfven wave having maximum growth rates at increasing angle to the magnetic field. The linear growth rates for the field-aligned magnetosonic and the Alfven oblique modes are investigated as a function of relative beam density, varying anisotropic pitch angle distributions for the various components, electron temperature, and electron heat flux.

Forage Density Gauging with Sr90 for Estimating Green Forage Yield in situ1

An accurate and reliable technique for estimating green forage yield in situ has been developed which utilizes beta particle attenuation by plant material.This technique involves the attenuation of beta particles from a strontium‐90 source by the vegetative mass of a forage stand. By measuring the intensity of the transmitted beta beam through different forage stands, a yield calibration curve was made which relates green forage yield to counts per minute. It was also found that the slope of the yield calibration curve was independent of the three crops tested as well as moisture content, thereby allowing a single yield calibration curve to be used for all forages.A field instrument was constructed to measure the practical value of density gauging to estimate green forage yield.Regression analysis of the experimental field data showed that this method accounted for 86% of the variation in yield and affirmed its usefulness in pasture research.

Coulomb Scattering of Polarized Electrons

The amount of longitudinal depolarization, L, and the asymmetry ratio, A, for a beta beam are expressed exactly in terms of F and G (the complex functions introduced by Mott). Approximate analytical expressions for L and A (corresponding to the second-order Born approximation) are also derived. The results are applied to a doublescattering experiment performed by de-Shalit. (M.H.R.)