Beta Beam Research Articles

Personnel dosimetry for the mixed beta (Kr-85)/photon (gamma, X-ray) beams using Harshaw 8814 TL dosimeters: Performance Test Applicability Study

Performance of Harshaw 8814 TL dosimeters was evaluated in the mixture of low energy beta (Kr-85, average energy 251 keV) and X-ray/gamma photon beams, when many doses obtained using existing dose calculation algorithms show a high bias. 264 TLDs were exposed at the Radiological and Environmental Sciences Laboratory to the pure Kr-85 energy beam as well as to different combinations of beta and photon beams of various energies (including Cs-137 and Co-60 gamma sources and M50, M200 and H300 X-ray beams). The TLDs were irradiated to different beta-to-photon dose ratios; 22 different combinations of radiation energy beams and beam dose ratios were tested. After exposure, the TLDs were readout at Brookhaven National Laboratory facility using a Harshaw 8800 reader. The doses were determined with the Harshaw Combined DOELAP dose calculation algorithm and compared to the known values. The results showed a significant deviation from the corresponding nominal values for some of the tested TLDs exposed to pure Kr-85 or a combination of Kr-85 and photon beam mixed energies. The different ratios of TL signals from chips 1–4 of the 8814 TL cards were analyzed, and an algorithm was proposed to identify the radiation beam energy to which each individual TLD was irradiated to. Finally, correction coefficients were developed which improves the performance of TL dosimetry dose calculation algorithm in the cases of exposure to a low energy beta beam and to a mixture of such beam with photons.

Graphene/porous GaN Schottky Betacell

Betavoltaic batteries have advantages over other batteries due to their high energy density, long life, insensitivity to the environment, and small size. This study aims to design a new structure for betavoltaic batteries using porous GaN with a wide energy bandgap. Many nanowires, coated with graphene, are formed on the surface of GaN. Graphene makes a Schottky junction with GaN and creates an internal electric field to separate electron-hole pairs in the depletion region. In our simulation, Ni63 with an activity of 1 mCi, radiant energy of 17 keV, and radiant flux of 6 Pa is used for beta radiation. The structure is simulated in a TCAD 3D simulator, and an auxiliary function written in C++ is employed to simulate the beta beam. This function provides the spatial distribution of the generated electron-hole pairs in GaN as the input data to our simulator to calculate the battery characteristics. The simulation results indicated that the open-circuit voltage, short-circuit current, fill factor (FF), output power, and efficiency were obtained as 1.22 V, 61.5 nA, 37%, 28.4 nW, and 28.4%, respectively. The effect of changes in the radioisotope source activity and temperature on the betavoltaic battery performance is also investigated. The use of porous GaN, along with the graphene as the semi-metal in Schottky junctions with GaN, has caused a good increase in the performance of our proposed betavoltaic cell in comparison with previously published works.

Comparing the Microdosimetric Kinetic Model-Predicted Proton RBE Values Using Constant and Variable Quadratic Beta Coefficients

In the current microdosimetric kinetic model (MKM) model for predicting the biological effects of therapeutic particles, the quadratic beta coefficient is assumed to be a constant independent of radiation types. However, many cell irradiation experiments have shown the variable beta coefficients for different beam qualities. The purpose of this study is to compare the predicted relative biological effectiveness (RBE) of protons using the MKM model with a constant beta value and beam quality (i.e., the microdosimetric quantity lineal energy) dependent beta values. We have spatially mapped the biological effects along the path of a mono-energetic 81.4 MeV proton beam using the high-throughput method. Clonogenic cell survival curves with twelve different beam qualities (dose mean lineal energy, yD) were obtained for the non-small cell lung cancer (NSCLC) cell line H460. The Cs-137 photon source was used as the reference. The microdosimetric data were obtained from the track-structure Monte Carlo simulations using Geant4-DNA with a water sphere (d = 2 μm) as the target. The alpha and beta coefficients for protons and reference photons were obtained from the linear-quadratic fit results of each survival curve. The beta coefficient of photons was selected as the constant beta value for MKM predictions. We calculated the alpha coefficient using the constant beta first and then using the variable beta for each proton beam quality. The MKM model predicted RBE values as a function of beam quality were then compared with the experimental RBE. The twelve evenly sampled yD values of the proton beam ranges from 1.38 to 21.77 keV/μm with the value of 12.93 keV/μm at the Bragg peak. The alpha and beta coefficients from Cs-137 photon source are 0.23 Gy-1 and 0.10 Gy-2. Our experiments have shown a general trend that the alpha and beta values of protons from experimental survival curves increase with the increase of yD. The experimental RBE increases from 0.99 (yD = 1.38 keV/μm) to 2.85 (yD = 21.77 keV/μm) in a rather non-linear way. Using the constant beta based MKM model, the predicted RBE (cell surviving fraction = 0.1) only varies from 1.00 to 1.12, nearly independent of the beam quality. In contrast, using the variable beta based MKM model, the predicted proton RBE increases as a function of yD and varies from 1.00 to 2.73. The relative difference between variable beta based MKM model prediction and the experimental RBE is within ±10%. From the results in this study, we conclude that using the experimentally determined variable beta values, MKM model can better predict the biological effects of protons. However, more experiments for different beam qualities and different cell lines are needed to further consolidate the conclusion made here.

Design of a neutrino source based on beta beams

“Beta beams” produce collimated pure electron (anti)neutrino beams by accelerating beta active ions to high energies and having them decay in a racetrack shaped storage ring of 7 km circumference, the decay ring. EUROnu beta beams are based on CERN infrastructures and existing machines. Using existing machines may be an advantage for the cost evaluation, but will also constrain the physics performance. The isotope pair of choice for the beta beam is He6 and Ne18. However, before the EUROnu studies one of the required isotopes, Ne18, could not be produced in rates that satisfy the needs for physics of the beta beam. Therefore, studies of alternative beta emitters, Li8 and B8, with properties interesting for a beta beam have been proposed and have been studied within EUROnu. These alternative isotopes could be produced by using a small storage ring, in which the beam traverses a target, creating the Li8 and B8 isotopes. This production ring, the injection linac and the target system have been evaluated. Measurements of the cross section of the reactions to produce the beta beam isotopes show interesting results. A device to collect the produced isotopes from the target has been developed and tested. However, the yields of Li8 and B8, using the production ring for production of Li8 and B8, is not yet, according to simulations, giving the rates of isotopes that would be needed. Therefore, a new method of producing the Ne18 isotope has been developed and tested giving good production rates. A 60 GHz ECRIS prototype, the first in the world, was developed and tested for ion production with contributions from EUROnu. The decay ring lattices for the Li8 and B8 have been developed and the lattice for He6 and Ne18 has been optimized to ensure the high intensity ion beam stability.43 MoreReceived 15 April 2014DOI:https://doi.org/10.1103/PhysRevSTAB.17.071002This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical Society

Production and release of ISOL beams from molten fluoride salt targets

In the framework of the Beta Beams project, a molten fluoride target has been proposed for the production of the required 101318Ne/s. The production and extraction of such rates are predicted to be possible on a circulating molten salt with 160MeV proton beams at close to 1MW power. As a most important step to validate the concept, a prototype has been designed and investigated at CERN-ISOLDE using a static target unit. The target material consisted of a binary fluoride system, NaF:LiF (39:61mol.%), with melting point at 649°C. The production of Ne beams has been monitored as a function of the target temperature and proton beam intensity. The prototype development and the results of the first online tests with 1.4GeV proton beam are presented in this paper.

Measuring Dirac CP-violating phase with intermediate energy beta beam facility

Taking the established nonzero value of $\theta_{13}$, we study the possibility of extracting the Dirac CP-violating phase by a beta beam facility with a boost factor $100<\gamma<450$. We compare the performance of different setups with different baselines, boost factors and detector technologies. We find that an antineutrino beam from $^6$He decay with a baseline of $L=1300$ km has a very promising CP discovery potential using a 500 kton Water Cherenkov (WC) detector. Fortunately this baseline corresponds to the distance between FermiLAB to Sanford underground research facility in South Dakota.

Angular Distribution and Cross Section Measurement of the6Li(3He,n)8B Reaction at 5.8 MeV

The reaction 6 Li( 3 He,n) 8 B was studied at Laboratori Nazionali di Legnaro in the framework of the EUROnu Design Study for a Beta Beam facility at CERN. The 8 B production cross section was determined through neutron angular distribution by using the time-of-flight technique. Thanks to the high statistics achieved, the neutron angular distribution for the population of the 8 B first excited state has been measured for the first time. Discrepancies with other available data sets for 8 B ground state population are discussed and interpreted in the framework of DWBA calculations. Further measurements at beam energies above 10 MeV are needed to clarify the behaviour of the angular distribution.

Validation of electro-thermal simulation with experimental data to prepare online operation of a molten salt target at ISOLDE for the Beta Beams

The main objective of the Beta Beams is to study oscillation property of pure electrons neutrinos. It produces high energy beams of pure electron neutrinos and anti-neutrinos for oscillation experiments by beta decay of 6He and 18Ne radioactive ion beams, stored in a decay ring at γ=100. The production of 6He beam has already been accomplished using a thick beryllium oxide target. However, the production of the needed rate of 18Ne has proven to be more challenging. In order to achieve the requested yield for 18Ne a new high power target design based on a circulating molten salt loop has been proposed. To verify some elements of the design, a static molten salt target prototype has been developed at ISOLDE and operated successfully. This paper describes the electro-thermal study of the molten salt target taking into account the heat produced by Joule effect, radiative heat exchange, active water cooling due to forced convection and air passive cooling due to natural convection. The numerical results were compared with the available experimental data in order to validate the model. This approach allows one to improve the reliability of the model, which will help to predict the thermo-mechanical impact of the required targets for future facilities such as HIE-ISOLDE and the Beta-Beams.

High intensity neutrino oscillation facilities in Europe

The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fr\'ejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of {\mu}+ and {\mu}- beams in a storage ring. The far detector in this case is a 100 kt Magnetised Iron Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular 6He and 18Ne, also stored in a ring. The far detector is also the MEMPHYS detector in the Fr\'ejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.

Beta Beams in the CERN complex: PS studies

For the Beta Beams to become a solid option for a future neutrino-physics facility at CERN, it is fundamental to demonstrate the feasibility of storing and accelerating the Beta Beams ions in the PS and SPS. This work identifies the key issues that should be assessed for the PS, presents the status of the ongoing studies and, in particular, discusses the choice of the injection energy and recent space-charge measurements.

Collection device for the production of 8Li and 8B radioactive ions

The goal of the European project EUROnu is the study of different ways to produce the future neutrino beams. One of them, proposed by C. Rubbia, is based on the production of 8Li and 8B nuclei and their post-acceleration. Within the "beta beams" work package of this project, our task is to study experimentally the production and collection efficiency of these 2 nuclei. Our R&D work is organised in two phases: first – design and construction of a collection device which will be validated with 8Li; second – experimental study of the possible ways to extract 8B from the collection device.

Future R&D experiments for Super-Beams, Neutrino Factories and Beta-Beams

There are three principle options for future beam based neutrino oscillation facilities that could discover and measure CP-violation in the lepton sector. These are conventional Super-Beams, Neutrino Factories and Beta Beams. Several projects have been taking place world-wide to study examples of these facilities. In Europe, one of the most important of these is the Framework Programme 7 supported project, EUROnu. These projects are in the process of identifying experimental R&D work that must be done before a technical design of the facility can be finalised and construction started. This paper will summarise this work for each type of facility, based largely on what has been done in EUROnu.

Opportunities for neutrino experiments at ISOLDE

A molten salt target is currently proposed for the production of high rates of 18Ne required for the beta beams project. Intermediate proton energy beams at close to 1 MW power are used on a circulating molten NaF eutectic to produce and extract 1×1013 18Ne/s.A conceptual design of such a circulating loop is presented. The application of a molten salt target for the monitoring of noble gas production is discussed with respect to the planned experimental program, which will be used to validate the proposed concept. Furthermore, a systematic experimental study on the production and release of gaseous and volatile elements from molten sodium-based targets, in preparation at CERN-ISOLDE, is presented.

Accelerators for future neutrino facilities: strengths and challenges

Several different ideas have been put forward for future neutrino facilities, including a high-power conventional neutrino beam (a "Superbeam" facility), a Beta Beam facility based on stored beta-unstable ion beams, and a Neutrino Factory based on stored muon beams. Each of these has its advantages and disadvantages, and these are described here. After briefly describing the physics context, the various options will be described and their respective strengths and challenges indicated. The supporting R&D programs will be briefly discussed and a few specific technical questions for each facility will be outlined.

Neutrino factory and beta beam: accelerator options for future neutrino experiments

Two accelerator options for producing intense neutrino beams are described – a Neutrino Factory based on stored muon beams and a Beta Beam facility based on stored beams of beta unstable ions. Technical challenges for each are described and current R&D efforts aimed at mitigating these challenges are indicated. Progress is being made in the design of both types of facility, each of which would extend the state-of-the-art in accelerator science.

Search for new physics with neutrinos at radioactive ion beam facilities

We propose applications of radioactive ion beam facilities to investigate physics beyond the Standard Model. In particular, we focus upon the search for sterile neutrinos and the possible measurement of coherent neutrino-nucleus scattering, by means of a low-energy beta beam with a Lorentz boost factor $\ensuremath{\gamma}\ensuremath{\approx}1$. In both cases, we consider $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$ ions as neutrino sources. In the considered setup, the collected radioactive ions are sent inside a $4\ensuremath{\pi}$ detector. For the first application, we provide the number of events associated with neutrino-nucleus coherent scattering, when the detector is filled with a noble liquid. For the sterile search, we consider that the spherical detector is filled with a liquid scintillator, and that the neutrino detection channel is inverse beta decay. We provide the exclusion curves for the sterile neutrino mixing parameters, based upon the $3+1$ formalism, depending upon the achievable ion intensity. Our results are obtained both from total rates, and by including spectral information with binning in energy and in distance. The proposed experiment represents a possible alternative to clarify the current anomalies observed in neutrino experiments.

Beta Beams for Neutrino Production

To use accelerated beta active radioactive ions to produce collimated high energy neutrino beams was proposed by P. Zuchelli in 2002. Since then, several ideas related to how to design Beta Beam facilities have been studied. Design studies of an accelerator complex, based on CERN accelerators, have been supported by research programs within the European Commisison FP6 and FP7 frameworks (EURISOL Design Study and EUROnu). In these studies 6He and 18Ne are used as beta emitters to produce antineutrinos and neutrinos respectively. Alternative isotopes for neutrino beam production, 8Li and 8B, are investigated in the now ongoing study, EUROnu. Due to the higher reaction Q-value of these ions, the resulting neutrino energies are higher. The isotopes we need for neutrino beams have to be produced in large quantities using non conventional methods. Latest research on production of isotopes that are presently considered for Beta Beams will be discussed.The work achieved gives a good ground to propose the Beta Beam, which is based on known technology, for neutrino production. In this status review we concentrate on technical issues related to a possible Beta Beam facility using the CERN infrastructure.

Requirements for a new detector at the South Pole receiving an accelerator neutrino beam

There are recent considerations to increase the photomultiplier density in the IceCube detector array beyond that of DeepCore, which will lead to a lower detection threshold and a huge fiducial mass for the neutrino detection. This initiative is known as "Phased IceCube Next Generation Upgrade" (PINGU). We discuss the possibility to send a neutrino beam from one of the major accelerator laboratories in the Northern hemisphere to such a detector. Such an experiment would be unique in the sense that it would be the only neutrino beam where the baseline crosses the Earth's core. We study the detector requirements for a beta beam, a neutrino factory beam, and a superbeam, where we consider both the cases of small theta_13 and large theta_13, as suggested by the recent T2K and Double Chooz results. We illustrate that a flavor-clean beta beam best suits the requirements of such a detector, in particular, that PINGU may replace a magic baseline detector for small values of theta_13 -- even in the absence of any energy resolution capability. For large theta_13, however, a single-baseline beta beam experiment cannot compete if it is constrained by the CERN-SPS. For a neutrino factory, because of the missing charge identification possibility in the detector, a very good energy resolution is required. If this can be achieved, especially a low energy neutrino factory, which does not suffer from the tau contamination, may be an interesting option for large theta_13. For the superbeam, where we use the LBNE beam as a reference, electron neutrino flavor identification and statistics are two of the main limitations. Finally, we demonstrate that, at least in principle, neutrino factory and superbeam can measure the density of the Earth's core to the sub-percent level for sin^2 2theta_13 larger than 0.01.

The effect of gas mixing and biased disc voltage on the preglow transient of electron cyclotron resonance ion source

The effect of gas mixing and biased disc voltage on the preglow of electron cyclotron resonance ion source plasma has been studied with the AECR-U type 14 GHz ion source. It was found that gas mixing has a significant effect on the preglow. The extracted transient beam currents and efficiency of the heavier species increase, while the currents and efficiency of the lighter species decrease when gas mixing is applied. The effect of the biased disc was found to be pronounced in continuous operation mode in comparison to preglow. The data provide information on the time scales of the plasma processes explaining the effects of gas mixing and biased disc. The results also have implications on production of radioactive ion beams in preglow mode for the proposed Beta Beam neutrino factory.

Low energy Superbeams, Beta beams and the Neutrino Factory

The world neutrino community is currently investigating the best way forward to address the value of θ 13 , the mass hierarchy and possible CP violation in the neutrino sector. This presentation describes the status of performance studies and R&D concerning Low energy Superbeams, Beta beams and a Neutrino Factory.