Statistical Signal Processing and Detector Optimization in Project 8

Despite the unambiguous discovery of non-zero neutrino masses from flavor oscillation experiments, a direct measurement of the absolute mass scale of the neutrino remains elusive to experimentalists. Project 8 is a tritium endpoint experiment utilizing Cyclotron Radiation Emission Spectroscopy (CRES), a novel, high-precision spectroscopic technique, in order to establish the absolute neutrino mass scale. In this document, I investigate the statistically motivated limits to CRES signal detection and parameter estimation, as well as the resultant consequences on optimal detector configuration. I implement and test an application of the Viterbi algorithm for CRES signal reconstruction, yielding the first derived limits on the minimal detection criteria. I then present an original derivation of the Cramér-Rao Lower Bound of the start frequency resolution for realistic CRES signals, along with estimators yielding near-optimal performance. Finally, these improved detection and reconstruction algorithms lead into a discussion of optimal detector design.Ph.D

High-resolution spectroscopy of gaseous 83m Kr conversion electrons with the KATRIN experiment

© 2020 The Author(s). Published by IOP Publishing Ltd. In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous 83mKr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The obtained results represent one of the major commissioning milestones for the subsequent direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the KATRIN beamline. Precise measurement of the narrow K-32, L3-32, and N2,3-32 conversion electron lines allowed to verify the eV-scale energy resolution of the KATRIN main spectrometer necessary for competitive measurement of the absolute neutrino mass scale

Muon-induced background in the KATRIN main spectrometer

The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β-particles from tritium β-decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background. Keywords: Cosmic-ray muon backgrounds; Electrostatic spectrometer; Neutrino massUnited States. Department of Energy (Grant DE-FG02-97ER41020)United States. Department of Energy (Grant DE-FG02-94ER40818)United States. Department of Energy (Grant DE-SC0004036)United States. Department of Energy (Grant DE-FG02-97ER41033)United States. Department of Energy (Grant DE-FG02-97ER41041)United States. Department of Energy (Grant DE-AC02-05CH11231)United States. Department of Energy (Grant DE-SC0011091)United States. Department of Energy (Grant DE-SC0019304

First transmission of electrons and ions through the KATRIN beamline

The Karlsruhe Tritium Neutrino (KATRIN) experiment is a large-scale effort to probe the absolute neutrino mass scale with a sensitivity of 0.2 eV (90% confidence level), via a precise measurement of the endpoint spectrum of tritium β-decay. This work documents several KATRIN commissioning milestones: the complete assembly of the experimental beamline, the successful transmission of electrons from three sources through the beamline to the primary detector, and tests of ion transport and retention. In the First Light commissioning campaign of autumn 2016, photoelectrons were generated at the rear wall and ions were created by a dedicated ion source attached to the rear section; in July 2017, gaseous83mKr was injected into the KATRIN source section, and a condensed83mKr source was deployed in the transport section. In this paper we describe the technical details of the apparatus and the configuration for each measurement, and give first results on source and system performance. We have successfully achieved transmission from all four sources, established system stability, and characterized many aspects of the apparatus.United States. Department of Energy (Grant DEFG02-97ER41020)United States. Department of Energy (Grant DE-FG02-94ER40818)United States. Department of Energy (Grant DE-SC0004036)United States. Department of Energy (Grant DE-FG02-97ER41033)United States. Department of Energy (Grant DE-FG02- 97ER41041)United States. Department of Energy (Grant DE-AC02-05CH11231)United States. Department of Energy (Grant DE-SC0011091

The KATRIN superconducting magnets: overview and first performance results

The KATRIN experiment aims for the determination of the effective electron anti-neutrino mass from the tritium beta-decay with an unprecedented sub-eV sensitivity. The strong magnetic fields, designed for up to 6 T, adiabatically guide β-electrons from the source to the detector within a magnetic flux of 191 Tcm 2 . A chain of ten single solenoid magnets and two larger superconducting magnet systems have been designed, constructed, and installed in the 70-m-long KATRIN beam line. The beam diameter for the magnetic flux varies from 0.064 m to 9 m, depending on the magnetic flux density along the beam line. Two transport and tritium pumping sections are assembled with chicane beam tubes to avoid direct "line-of-sight" molecular beaming effect of gaseous tritium molecules into the next beam sections. The sophisticated beam alignment has been successfully cross-checked by electron sources. In addition, magnet safety systems were developed to protect the complex magnet systems against coil quenches or other system failures. The main functionality of the magnet safety systems has been successfully tested with the two large magnet systems. The complete chain of the magnets was operated for several weeks at 70% of the design fields for the first test measurements with radioactive krypton gas. The stability of the magnetic fields of the source magnets has been shown to be better than 0.01% per month at 70% of the design fields. This paper gives an overview of the KATRIN superconducting magnets and reports on the first performance results of the magnets. Keywords: Acceleration cavities and magnets superconducting (high-temperature superconductor; radiation hardened magnets; normal-conducting; permanent magnet devices; wigglers and undulators); Control systems; Cryogenics; Spectrometer

Locust: C++ software for simulation of RF detection

The Locust simulation package is a new C++ software tool developed to simulate the measurement oftime-varying electromagneticfields using RF detection techniques. Modularity andflexibility allowfor arbitrary input signals, while concurrently supporting tight integration with physics-basedsimulations as input. External signals driven by the Kassiopeia particle tracking package are discussed,demonstrating conditional feedback between Locust and Kassiopeia during software execution. Anapplication of the simulation to the Project 8 experiment is described. Locust is publicly available athttps://github.com/project8/locust_mc.United States. Department of Energy. Office of Science. Office of Nuclear Physics (Award DE-SC0011091)Pennsylvania State University. Early Career Award (Award DE-SC0019088)United States. Department of Energy (Contract DE-AC05-76RL01830)United States. Department of Energy (Award DE-FG02-97ER41020)United States. Department of Energy (Award DE-SC0012654)National Science Foundation (U.S.) (Award 1205100)National Science Foundation (U.S.) (Award 1505678)United States. Department of Energy. Laboratory Directed Research and Development (Contract DE-AC52-07NA27344

Cyclotron radiation emission spectroscopy signal classification with machine learning in project 8

© 2020 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft. The cyclotron radiation emission spectroscopy (CRES) technique pioneered by Project 8 measures electromagnetic radiation from individual electrons gyrating in a background magnetic field to construct a highly precise energy spectrum for beta decay studies and other applications. The detector, magnetic trap geometry and electron dynamics give rise to a multitude of complex electron signal structures which carry information about distinguishing physical traits. With machine learning models, we develop a scheme based on these traits to analyze and classify CRES signals. Proper understanding and use of these traits will be instrumental to improve cyclotron frequency reconstruction and boost the potential of Project 8 to achieve world-leading sensitivity on the tritium endpoint measurement in the future

Electron radiated power in cyclotron radiation emission spectroscopy experiments

© 2019 American Physical Society. US. The recently developed technique of Cyclotron Radiation Emission Spectroscopy (CRES) uses frequency information from the cyclotron motion of an electron in a magnetic bottle to infer its kinetic energy. Here we derive the expected radio-frequency signal from an electron in a waveguide CRES apparatus from first principles. We demonstrate that the frequency-domain signal is rich in information about the electron's kinematic parameters and extract a set of measurables that in a suitably designed system are sufficient for disentangling the electron's kinetic energy from the rest of its kinematic features. This lays the groundwork for high-resolution energy measurements in future CRES experiments, such as the Project 8 neutrino mass measurement

Kassiopeia: a modern, extensible C++ particle tracking package

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease-of-use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur in flight such as bulk scattering and decay, and stochastic surface processes occurring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle's state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia.United States. Department of Energy. Office of Nuclear Physics (Award FG02-97ER41041)United States. Department of Energy. Office of Nuclear Physics (Award DE-FG02-06ER-41420