Simulation and measurement of the suppression of radon induced background in the KATRIN experiment

Wolf, J.; Harms, F.

doi:10.1063/1.5018997

Cited by 3 publications

(6 citation statements)

References 12 publications

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“…By extrapolating the results of the PS tests reported here and in [15], the expected radon-induced background rate due to the NEG material and the large surface of the Main Spectrometer was estimated to be of the order of 1 cps [11,17,33]. This value was confirmed by the commissioning measurements ( [34,35]). As such a large background rate would significantly reduce the sensitivity of KATRIN on m ν [11,26,33], this background class has to be further reduced by more than two orders of magnitude.…”

Section: Jinst 13 T10004supporting

confidence: 72%

“…In addition to the passive background reduction via the technique of a liquid-nitrogen-cooled copper baffle discussed here, further active suppression methods of background induced by magnetically stored electrons were investigated, such as a cyclic application of an electric dipole [37] in combination with a magnetic pulse [26,38,39], and electron cyclotron resonance [14,33]. The method of removing emanated Rn atoms from the active flux tube of a MAC-E filter is studied in more detail in measurements with the Main Spectrometer [34,35]. By combining all the background reduction techniques, a staged approach to reach conditions where the spectrometer is essentially free of radon-induced background is at hand for the KATRIN neutrino mass measurements.…”

Section: Jinst 13 T10004mentioning

confidence: 99%

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Impact of a cryogenic baffle system on the suppression of radon-induced background in the KATRIN Pre-Spectrometer

et al. 2018

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A : The KATRIN experiment will determine the effective electron anti-neutrino mass with a sensitivity of 200 meV/c 2 at 90% CL. The energy analysis of tritium β-decay electrons will be performed by a tandem setup of electrostatic retarding spectrometers which have to be operated at very low background levels of < 10 −2 counts per second. This benchmark rate can be exceeded by background processes resulting from the emanation of single 219,220 Rn atoms from the inner spectrometer surface and an array of non-evaporable getter strips used as main vacuum pump. Here we report on a the impact of a cryogenic technique to reduce this radon-induced background in electrostatic spectrometers. It is based on installing a liquid nitrogen cooled copper baffle in the spectrometer pump port to block the direct line of sight between the getter pump, which is the main source of 219 Rn, and the sensitive flux tube volume. This cold surface traps a large fraction of emanated radon atoms in a region outside of the active flux tube, preventing background there. We outline important baffle design criteria to maximize the efficiency for the adsorption of radon atoms, describe the baffle implemented at the KATIRN Pre-Spectrometer test set-up, and report on its initial performance in suppressing radon-induced background. K : KATRIN; non-evaporable getter; radon emanation; baffle; cold trap 1deceased 2Corresponding author arXiv:1808.09168v1 [physics.ins-det]

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Section: Jinst 13 T10004supporting

confidence: 72%

Section: Jinst 13 T10004mentioning

confidence: 99%

Impact of a cryogenic baffle system on the suppression of radon-induced background in the KATRIN Pre-Spectrometer

et al. 2018

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“…Therefore, only two out of three possible NEG pumps were installed (see figure 28). In combination with cryogenic baffles between the NEG pumps and the inner volume, the radon-induced background has been reduced to an acceptable level [61]. These measures reduced the effective pumping speed of 10 6 l/s for H 2 in the initial design to 2.5 × 10 5 l/s.…”

Section: Vacuum System Of the Main Spectrometermentioning

confidence: 99%

“…Decay of radon atoms in the volume. Another source of primary electrons is radon decay; in particular, short-lived radon isotopes such as 219 Rn (𝑡 1/2 = 3.9 s) and 220 Rn (𝑡 1/2 = 56 s), which can decay before they are pumped out [60,61]. Following the 𝛼-decay of a radon isotope, these background electrons can be produced by various processes [62].…”

Section: Jinst 16 T08015mentioning

confidence: 99%

The design, construction, and commissioning of the KATRIN experiment

Aker¹,

Altenmüller²,

Amsbaugh³

et al. 2021

J. Inst.

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The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns. K: Beam-line instrumentation (beam position and profile monitors, beam-intensity monitors, bunch length monitors); Spectrometers; Gas systems and purification; Neutrino detectors A X P : 2103.04755Neutrino-mass mode. This is the standard mode of operation to continually adjust the retarding voltage of the MS in the range of [ 0 − 40 eV; 0 + 50 eV] while tritium is in the system. This scanning range can be adjusted if required. The voltage and the time spent at each setting are defined by the Measurement Time Distribution (MTD) (figure 3). A typical run at a given voltage lasts between 20 s and 600 s; a full scan of the energy range given above takes about 2 h. Of these standard neutrino-mass runs, a small portion will be dedicated to sterile neutrino searches. These searches involve scanning much farther (order of keV) below the endpoint 0 .Calibration mode. To check the long-term system stability, calibration measurements are done regularly. The neutrino-mass mode is suspended for the duration of these measurement:• An energy calibration of the FPD (section 6) is performed weekly, which requires closing off the detector system from the main beamline for about 4 h.• The offset and the gain correction factor of the low-voltage readout in the high-voltage measurement chain needs to be calibrated based on standard reference sources (section 5.3.4). This requires stopping the precision monitoring of the MS retarding potential twice per week for about 0.5 h each.

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“…Another source of primary electrons is radon decay; in particular, short-lived radon isotopes such as 219 Rn (𝑡 1/2 = 3.9 s) and 220 Rn (𝑡 1/2 = 56 s), which can decay before they are pumped out [60,61]. Following the 𝛼-decay of a radon isotope, these background electrons can be produced by various processes [62].…”

Section: Decay Of Radon Atoms In the Volumementioning

confidence: 99%

The Design, Construction, and Commissioning of the KATRIN Experiment

Aker,

Altenmüller,

Amsbaugh

et al. 2021

Preprint

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Simulation and measurement of the suppression of radon induced background in the KATRIN experiment

Cited by 3 publications

References 12 publications

Impact of a cryogenic baffle system on the suppression of radon-induced background in the KATRIN Pre-Spectrometer

Impact of a cryogenic baffle system on the suppression of radon-induced background in the KATRIN Pre-Spectrometer

The design, construction, and commissioning of the KATRIN experiment

The Design, Construction, and Commissioning of the KATRIN Experiment

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