B. Monreal

Relativistic Cyclotron Radiation Detection of Tritium Decay Electrons as a New Technique for Measuring the Neutrino Mass

The shape of the beta-decay energy distribution is sensitive to the mass of the electron neutrino. Attempts to measure the endpoint shape of tritium decay have so far seen no distortion from the zero-mass form, thus placing an upper limit of m{sub {nu}}{sub {beta}}<2.3 eV. Here, we show that a new type of electron energy spectroscopy could improve future measurements of this spectrum and therefore of the neutrino mass. We propose to detect the coherent cyclotron radiation emitted by an energetic electron in a magnetic field. For mildly relativistic electrons, like those in tritium decay, the relativistic shift of the cyclotron frequency allows us to extract the electron energy from the emitted radiation. We present calculations for the energy resolution, noise limits, high-rate measurement capability, and systematic errors expected in such an experiment.

Monitoring of the operating parameters of the KATRIN Windowless Gaseous Tritium Source

The KArlsruhe TRItium Neutrino (KATRIN) experiment will measure the absolute mass scale of neutrinos with a sensitivity of m??=?200?meV/c2 by high-precision spectroscopy close to the tritium ?-decay endpoint at 18.6?keV. Its Windowless Gaseous Tritium Source (WGTS) is a ?-decay source of high intensity (1011?s?1) and stability, where high-purity molecular tritium at 30?K is circulated in a closed loop with a yearly throughput of 10?kg. To limit systematic effects the column density of the source has to be stabilized at the 10?3 level. This requires extensive sensor instrumentation and dedicated control and monitoring systems for parameters such as the beam tube temperature, injection pressure, gas composition and so on. In this paper, we give an overview of these systems including a dedicated laser-Raman system as well as several ?-decay activity monitors. We also report on the results of the WGTS demonstrator and other large-scale test experiments giving proof-of-principle that all parameters relevant to the systematics can be controlled and monitored on the 10?3 level or better. As a result of these works, the WGTS systematics can be controlled within stringent margins, enabling the KATRIN experiment to explore the neutrino mass scale with the design sensitivity.

Single-electron detection and spectroscopy via relativistic cyclotron radiation

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

The AMS-02 TRD for the international space station

The Alpha Magnetic Spectrometer (AMS-02) is an experiment which will be mounted on the international space station (ISS) to measure primary cosmic ray spectra in space. A key element is the transition radiation detector (TRD) to extract an e/sup +/ or p/sup -/ signal reducing the p/sup +/ or e/sup -/ background by a rejection factor 10/sup 2/--10/sup 3/ in an energy range from 10 to 300 GeV. This will be used in combination with an electromagnetic calorimeter to provide overall p/sup +/ rejection of 10/sup 6/ at 90% e/sup +/ efficiency. The detector consists of 20 layers of 6 mm diameter straw tubes alternating with 20 mm layers of polyethylene/polypropylene fleece radiator. The tubes are filled with a 4:1 mixture of Xe:CO/sub 2/ at 1 bar absolute pressure from a recirculating gas system designed to operate >3 years in space. There are in total 5248 straw tubes which are read out by a custom-made DAQ system in less than 80 /spl mu/s. The electronics must be low in power consumption and sustain the stringent requirements of operation in space. The construction of the detector and its electronics is presented in this paper.

Sensitivity of Neutrino Mass Experiments to the Cosmic Neutrino Background

The KATRIN neutrino experiment is a next-generation tritium beta decay experiment aimed at measuring the mass of the electron neutrino to better than 200 meV at 90% C.L. Because of its intense tritium source, KATRIN can also serve as a possible target for the process of neutrino capture, {nu}{sub e}+{sup 3}H{yields}{sup 3}He{sup +}+e{sup -}. The latter process, possessing no energy threshold, is sensitive to the cosmic neutrino background (C{nu}B). In this paper, we explore the potential sensitivity of the KATRIN experiment to the relic neutrino density. The KATRIN experiment is sensitive to a C{nu}B overdensity ratio of 2.0x10{sup 9} over standard concordance model predictions (at 90% C.L.), addressing the validity of certain speculative cosmological models.

Search for Stable Strange Quark Matter in Lunar Soil

We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from A = 42 to A = 70 amu for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than 10(-16) is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

Deuterons and space-momentum correlations in high energy nuclear collisions

Using a microscopic transport model together with a coalescence afterburner, we study the formation of deuterons in Au+Au central collisions at [radical] (s) =200A GeV. It is found that the deuteron transverse momentum distributions are strongly affected by the nucleon space-momentum correlations, at the moment of freeze-out, which are mostly determined by the number of rescatterings. This feature is useful for studying collision dynamics at ultrarelativistic energies. [copyright] [ital 1999] [ital The American Physical Society]

Full simulation of the Sudbury Neutrino Observatory proportional counters

The third phase of the Sudbury Neutrino Observatory (SNO) experiment added an array of 3He proportional counters to the detector. The purpose of this neutral-current detection (NCD) array was to observe neutrons resulting from neutral-current solar-neutrino–deuteron interactions. We have developed a detailed simulation of current pulses from NCD array proportional counters, from the primary neutron capture on 3He through NCD array signal-processing electronics. This NCD array MC simulation was used to model the alpha-decay background in SNOs third-phase 8B solar-neutrino measurement.

Proton and deuteron distributions as signatures for collective particle dynamics and event shape geometries at ultrarelativistic energies

We present predictions for the formation of (anti)nuclear bound states in nucleus-nucleus reactions at ultrarelativistic energies. The phase-space coalescence method is used in combination with RQMD v2.4 transport calculations to demonstrate the relevance of particle production, as well as the longitudinal and transverse flow components. The formation of deuterons follows an approximate scaling law proportional to the relative freeze-out densities of nucleons and produced secondaries. For antideuterons, an additional suppression appears that is proportional to the number of nucleons, pointing toward multiple rescattering and absorption prior to freeze out. {copyright} {ital 1999} {ital The American Physical Society}

Project 8 Phase III Design Concept

We present a working concept for Phase III of the Project 8 experiment, aiming to achieve a neutrino mass sensitivity of