Ionization by Nuclear Transitions

Freedman, M. S.

doi:10.1007/978-1-4684-2799-8_13

Cited by 4 publications

(5 citation statements)

References 5 publications

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“…When an α-particle passes the fast inner atomic electrons, the direct collision process can lead to the emission of a shake-off electron [26][27][28]. The resulting electron energy spectrum shows a higher-order potential dependence [29] because the decay energy is shared between the α-particle and the emitted electron, which carries only a small fraction, usually of the same order of magnitude as the shell binding energy E b .…”

Section: Particle Generationmentioning

confidence: 99%

Validation of a model for radon-induced background processes in electrostatic spectrometers

Wandkowsky

Drexlin

Fränkle

et al. 2013

J. Phys. G: Nucl. Part. Phys.

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The Karlsruhe Tritium Neutrino (KATRIN) experiment investigating tritium βdecay close to the endpoint with unprecedented precision has stringent requirements on the background level of less than 10 −2 counts per second. Electron emission during the α-decay of 219,220 Rn atoms in the electrostatic spectrometers of KATRIN is a serious source of background exceeding this limit. In this paper we compare extensive simulations of Rn-induced background to specific measurements with the KATRIN prespectrometer to fully characterize the observed Rn-background rates and signatures and determine generic Rn emanation rates from the pre-spectrometer bulk material and its vacuum components.

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Section: Particle Generationmentioning

confidence: 99%

Validation of a model for radon-induced background processes in electrostatic spectrometers

Wandkowsky

Drexlin

Fränkle

et al. 2013

J. Phys. G: Nucl. Part. Phys.

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“…A nuclear α-decay leads to a perturbation of the atomic shells, as the electrons experience the passage of the outgoing α-particle through the atomic orbitals, as well as the sudden change ∆Z = Z − Z of the Coulomb potential of the nucleus (initial state: Z = 86 for radon, final state: Z = 84 for polonium) [20]. The impact of both processes on innershell (K, L, M) electrons is different than on outer-shell (N or higher) electrons due to the largely different orbital velocities.…”

Section: Inner Shell Shake-off Processesmentioning

confidence: 99%

“…For inner shells, electron shake-off (SO) is caused by the direct collision process [20,21,22]. In this case, the α-particle, which has already gained 99% of its final kinetic Table 1: The table gives an overview of the relative probabilities P i (per α-decay) of the dominant IC lines and of the corresponding electron energies E kin for 219 Rn, as measured by [18].…”

Section: Inner Shell Shake-off Processesmentioning

confidence: 99%

“…The SO subroutine then uses the generated random number to initiate an SO process with the corresponding probabilities for the individual (sub-)shells. Consequently, this can in some rare cases result in the emission of multiple SO electrons [20]. For the determination of the SO electron energy the acceptance-rejection method [34] is applied to eq.…”

Section: The Radon Event Generatormentioning

confidence: 99%

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Modeling of electron emission processes accompanying radon-α-decays within electrostatic spectrometers

Wandkowsky¹,

Drexlin²,

Fränkle³

et al. 2013

New J. Phys.

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Electrostatic spectrometers utilized in high-resolution βspectroscopy studies such as in the Karlsruhe Tritium Neutrino (KATRIN) experiment have to operate with a background level of less than 10 −2 counts per second. This limit can be exceeded by even a small number of 219,220 Rn atoms being emanated into the volume and undergoing α-decay there. In this paper we present a detailed model of the underlying background-generating processes via electron emission by internal conversion, shake-off and relaxation processes in the atomic shells of the 215,216 Po daughters. The model yields electron energy spectra up to 400 keV and electron multiplicities of up to 20 which are compared to experimental data.

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“…Sources of primary stored electrons include β-decays of tritium molecules (HT, T 2 ) and processes occurring during α-decays of the radon isotopes 219,220 Rn. The energy distribution of these primary electrons varies by more than five orders of magnitude from the eV level up to about one hundred keV [22][23][24][25][26][27][28]. However, in terms of cyclotron frequency f c (B, γ) this implies a variation of about 20% (1 ≤ γ ≤ 1.2) only.…”

Section: The Working Principle Of Ecr At a Katrin Spectrometermentioning

confidence: 99%

Stochastic heating by ECR as a novel means of background reduction in the KATRIN spectrometers

et al. 2012

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Abstract. The primary objective of the KATRIN experiment is to probe the absolute neutrino mass scale with a sensitivity of 200 meV (90% C.L.) by precision spectroscopy of tritium β-decay. To achieve this, a low background of the order of 10 −2 cps in the region of the tritium β-decay endpoint is required. Measurements with an electrostatic retarding spectrometer have revealed that electrons, arising from nuclear decays in the volume of the spectrometer, are stored over long time periods and thereby act as a major source of background exceeding this limit. In this paper we present a novel active background reduction method based on stochastic heating of stored electrons by the well-known process of electron cyclotron resonance (ECR). A successful proofof-principle of the ECR technique was demonstrated in test measurements at the KATRIN pre-spectrometer, yielding a large reduction of the background rate. In addition, we have carried out extensive Monte Carlo simulations to reveal the potential of the ECR technique to remove all trapped electrons in a few ms with negligible loss of measurement time in the main spectrometer. This would allow the KATRIN experiment attaining its full physics potential.

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Ionization by Nuclear Transitions

Cited by 4 publications

References 5 publications

Validation of a model for radon-induced background processes in electrostatic spectrometers

Validation of a model for radon-induced background processes in electrostatic spectrometers

Modeling of electron emission processes accompanying radon-α-decays within electrostatic spectrometers

Stochastic heating by ECR as a novel means of background reduction in the KATRIN spectrometers

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