This paper introduces an experimental probe of the sterile neutrino with a novel, high-intensity source of electron antineutrinos from the production and subsequent decay of 8 Li. When paired with an existing ∼1 kton scintillator-based detector, this Eν =6.4 MeV source opens a wide range of possible searches for beyond standard model physics via studies of the inverse beta decay interaction νe + p → e + + n. In particular, the experimental design described here has unprecedented sensitivity toνe disappearance at ∆m 2 ∼ 1 eV 2 and features the ability to distinguish between the existence of zero, one, and two sterile neutrinos.PACS numbers: 14.60.Pq, 14.60.StThe beta decay-at-rest of 8 Li produces an isotropic electron antineutrino flux with an average energy of 6.4 MeV. An underground liquid scintillator based detector can be used to detect these antineutrinos via the inverse beta decay (IBD) processν e + p → e + + n. The antineutrino rate and energy, peaking at 9 MeV, can be fully reconstructed by the detector. Precise energy and vertex reconstruction opens the possibility of searching for antineutrino disappearance due to oscillations, which, in the simplest two-neutrino form, has the probabilitywhere θ is the disappearance mixing angle; ∆m 2 (eV 2 ) is the squared mass splitting; L is the distance (in meters) from the antineutrino source to the detector; and E (MeV) is the antineutrino energy. This probability is maximized in the range of ∆m 2 ∼ E/L. An existing large scintillator-based antineutrino detector with a diameter of O(10 m), when combined with an 8 Li isotope decay-at-rest source, is sensitive to oscillations at ∆m 2 ∼ 1 eV 2 . This is an oscillation region of high interest due to anomalies that have been observed in the data from LSND [1], MiniBooNE [2], short-baseline reactor studies [3], and gallium source calibration runs [4]. These anomalies are often interpreted as being due to sterile neutrinos [5][6][7][8] and have motivated the development of the IsoDAR (Isotope Decay-At-Rest) concept.IsoDAR-style sources have been considered before [9][10][11]. The design presented here, consisting of an ion source, cyclotron, and target, is the first with a sufficiently high antineutrino flux to address the existence of one or more sterile neutrinos. 5 IBD interactions in a five year run. Such events allow a definitive search for antineutrino oscillations with the added ability to distinguish between models with one and two sterile neutrinos. A sample of more than 7200ν e -electron scatters is also accumulated during this time and can be used as a sensitive electroweak probe.The charged particle beam, used for electron antineutrino production, originates with a 60 MeV/amu cyclotron accelerating 5 mA of H + 2 ions. The design of this compact cyclotron [15] is ongoing and is envisaged as the injector for the accelerator system of the DAEδALUS physics program [16,17]. The IsoDAR design calls for about a factor of six increase in intensity compared to compact cyclotrons used in the medical isotope industry. ...
This whitepaper describes the status of the DAEδALUS program for development of high power cyclotrons as of the time of the final meeting of the Division of Particles and Fields 2013 Community Study ("Snowmass"). We report several new results, including a measurement capability between ∼4 and 12 degrees on the CP violating parameter in the neutrino sector. Past results, including the capability of the IsoDAR high ∆m 2 νe disappearance search, are reviewed. A discussion of the R&D successes, including construction of a beamline teststand, and future plans are provided. This text incorporates short whitepapers written for subgroups in the Intensity Frontier and Frontier Capabilities Working Groups that are available on the Snowmass website.
In this paper we present the results of GEANT4 simulations of the production of surface muons as a function of energy of the incident protons on a graphite target. A validation of the GEANT4 hadronic physics models has been performed by comparing the results with experimental data from the Lawrence Radiation Laboratory, United States. Considering the ISIS muon target as a reference, simulations have been performed to optimize the pion and muon production. Of particular significance, we predict that optimal surface muon production occurs at a relatively modest proton energy of 500 MeV. This will be of importance for the development of future SR facilities.
The IsoDAR sterile-neutrino search requires a very high intensity neutrino source. For IsoDAR, this high intensity is produced using the high neutron flux from a 60 MeV, 10 mA proton beam striking a beryllium target that floods a sleeve of highly-enriched Li-7. Through neutron capture the Li-7 is transmuted to Li-8, which beta-decays giving the desired high neutrino flux for very-short baseline neutrino experiments. The target can be placed very close to can existing large neutrino detector, which is typically located deep underground to reduce backgrounds. With such a setup, it is necessary to design a shielding enclosure for the target to prevent neutrons from causing unacceptable activation of the rock walls close to the target. Various materials have been studied including steel to thermalize the high energy neutrons and two new types of concrete developed by Jefferson Laboratory, one very light with shredded plastic aggregate, and the other one enriched with high quantities of boron. The shielding is asymmetrical, having a larger thickness towards the detector in order to suppress the neutron and gamma background in the neutrino detector. Simulation results for rock activation and for detector backgrounds are presented.
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