A novel technique of extracting UCN lifetimes from storage bottle measurements dominated by scattering losses

Abstract

Neutron lifetime is a critical parameter in the Standard Model. Its measurements using, particularly, the beamline and ultracold neutron storage techniques reveals serious tension. The status of the tension between various measurements have been presented, in light of the insights provided by the $\beta$-decay correlation measurements. When ultracold neutrons are stored in material bottles, they can be lost to various processes, such as $\beta$-decay and up-scattering on material walls. Here, we revisit the lifetime measurement in a material storage bottle, dominated by losses from scattering off the walls of the storage chamber. The neutron energy spectra and its associated uncertainties were, for the first time, well characterized. Such models have been used in the extraction of mean time between wall bounces, which is a key parameter for neutron storage disappearance experiments in search of neutron oscillation. A comparison between the loss model and the number of neutrons stored in a single chamber, used for the neutron electric dipole moment search, allowed us to extract a neutron lifetime of ${\tau }_n^{\ast }=879(+158/-78{)}_{\text{stat.}}(+230/-114{)}_{\text{sys.}}\text{s (68.3\% C.I.)}$. Though the uncertainty on this lifetime is not competent with currently available measurements, the highlight of this work is that, we precisely identify the systematic sources of uncertainty that contribute to the neutron lifetime measurements in material storage bottles, namely from the uncertainty in the energy spectra, as well as the storage chamber parameters of Fermi potential and loss per bounce parameter. In doing so, we finally highlight the underestimation of the uncertainties in the previous Monte Carlo simulations of experiments using ultracold neutron storage in material bottles.

arXiv comment20 pages, 7 figures, 4 tables. Long unedited version, with extra details. This is an independent analysis, and not a part of nEDM@PSI collaboration

References in corpus (56)

• Big Bang Nucleosynthesis: 2015
• Measurement of the permanent electric dipole moment of the neutron
• Primordial Nucleosynthesis in the Precision Cosmology Era
• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• Tests of the standard electroweak model in beta decay
• Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating
• Improved Determination of the Neutron Lifetime
• Improved Calculation of Electroweak Radiative Corrections and the Value of V_ud
• Superallowed 0+ --> 0+ nuclear beta decays: 2014 critical survey, with precise results for Vud and CKM unitarity
• Sharpening the predictions of big-bang nucleosynthesis
• Dark Matter Interpretation of the Neutron Decay Anomaly
• New physics searches in nuclear and neutron $\beta$ decay
• Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam
• Beta Decays and Non-Standard Interactions in the LHC Era
• Measurement of the neutron lifetime using an asymmetric magneto- gravitational trap and in situ detection
• Is the Unitarity of the quark-mixing-CKM-matrix violated in neutron $\beta$-decay?
• Determination of the Weak Axial Vector Coupling from a Measurement of the Beta-Asymmetry Parameter A in Neutron Beta Decay
• Neutron Lifetime and Axial Coupling Connection
• The CKM unitarity problem: A trace of new physics at the TeV scale?
• Neutron lifetime measurements with the big gravitational trap for ultracold neutrons
• Measurement of the Neutron Lifetime by Counting Trapped Protons in a Cold Neutron Beam
• Magnetic Trapping of Neutrons
• Neutron lifetime measurements using gravitationally trapped ultracold neutrons
• Neutron lifetime puzzle and neutron -- mirror neutron oscillation
• Precision Measurement of the Neutron Beta-Decay Asymmetry
• New result for the neutron $\beta$-asymmetry parameter $A_0$ from UCNA
• Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons
• Dynamic stabilization of the magnetic field surrounding the neutron electric dipole moment spectrometer at the Paul Scherrer Institute
• Apparatus for Measurement of the Electric Dipole Moment of the Neutron using a Cohabiting Atomic-Mercury Magnetometer
• Exotic decay channels are not the cause of the neutron lifetime anomaly
• Measurement of the Neutron Lifetime Using a Proton Trap
• Improved determination of the $\beta$-${\overline{\nu }}_e$ angular correlation coefficient $a$ in free neutron decay with the $a$SPECT spectrometer
• Measurement of the Proton Asymmetry Parameter C in Neutron Beta Decay
• Measurement of the neutron $\beta$-asymmetry parameter $A_0$ with ultracold neutrons
• A search for neutron to mirror-neutron oscillations
• A New World Average Value for the Neutron Lifetime
• Neutron lifetime and dark decay of the neutron and hydrogen
• Optically Pumped Cs Magnetometers Enabling a High-Sensitivity Search for the Neutron Electric Dipole Moment
• Magnetic trapping of ultracold neutrons
• Magnetic field uniformity in neutron electric dipole moment experiments
• Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly
• Observation of gravitationally induced vertical striation of polarized ultracold neutrons by spin-echo spectroscopy
• Limit on the Fierz Interference Term b from a Measurement of the Beta Asymmetry in Neutron Decay
• Neutron lifetime measurements and effective spectral cleaning with an ultracold neutron trap using a vertical Halbach octupole permanent magnet array
• Ultracold neutron detection with 6Li-doped glass scintillators, NANOSC: a fast ultracold neutron detector for the nEDM experiment at the Paul Scherrer Institute
• Gravitational Depolarization of Ultracold Neutrons: Comparison with Data
• The MCUCN simulation code for ultracold neutron physics
• First direct constraints on Fierz interference in free neutron $\beta$ decay
• Gravitationally enhanced depolarization of ultracold neutrons in magnetic field gradients, and implications for neutron electric dipole moment measurements
• Demonstration of sensitivity increase in mercury free-spin-precession magnetometers due to laser-based readout for neutron electric dipole moment searches
• Space-Based Measurement of the Neutron Lifetime using Data from the Neutron Spectrometer on NASA's MESSENGER Mission
• nEDM experiment at PSI: data-taking strategy and sensitivity of the dataset
• A meta-analysis of neutron lifetime measurements
• Mapping of the magnetic field to correct systematic effects in a neutron electric dipole moment experiment
• Statistical sensitivity of the nEDM apparatus at PSI to neutron mirror-neutron oscillations
• Ultracold Neutron Storage Simulation Using the Kassiopeia Software Package