Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment
Abstract The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium $$\upbeta $$...
| Main Authors: | , , , , , , , , , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
Springer Berlin Heidelberg
2021
|
| Online Access: | https://hdl.handle.net/1721.1/136902 |
| Summary: | Abstract
The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium
$$\upbeta $$
β
-decay endpoint region with a sensitivity on
$$m_\nu $$
m
ν
of 0.2
$$\hbox {eV}/\hbox {c}^2$$
eV
/
c
2
(90% CL). For this purpose, the
$$\upbeta $$
β
-electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6 keV. A dominant systematic effect of the response of the experimental setup is the energy loss of
$$\upbeta $$
β
-electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes; the latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95%
$$\hbox {T}_2$$
T
2
gas mixture at 30 K, as used in the first KATRIN neutrino-mass analyses, as well as a
$$\hbox {D}_2$$
D
2
gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of
$$\sigma (m_\nu ^2)< {{10}^{-2}}{\hbox {eV}^{2}}$$
σ
(
m
ν
2
)
<
10
-
2
eV
2
[1] in the KATRIN neutrino-mass measurement to a subdominant level. |
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