Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

Zimmer, O.; Golub, R.

doi:10.1103/physrevc.92.015501

Cited by 25 publications

(22 citation statements)

References 87 publications

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“…By improvement of the poor vacuum conditions prevailing in the connected storage vessel output degradation might not be an issue. The source SUN-2 studied here is a prototype for the SuperSUN UCN source comprised of a 12 liter converter vessel with a magnetic multipole reflector [81], which is currently under construction at the ILL.…”

Section: E Ucn Density Determinationmentioning

confidence: 99%

Comparison of ultracold neutron sources for fundamental physics measurements

et al. 2017

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Ultracold neutrons (UCNs) are key for precision studies of fundamental parameters of the neutron and in searches for new CP violating processes or exotic interactions beyond the Standard Model of particle physics. The most prominent example is the search for a permanent electric dipole moment of the neutron (nEDM). We have performed an experimental comparison of the leading UCN sources currently operating. We have used a 'standard' UCN storage bottle with a volume of 32 liters, comparable in size to nEDM experiments, which allows us to compare the UCN density available at a given beam port.

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Section: E Ucn Density Determinationmentioning

confidence: 99%

Comparison of ultracold neutron sources for fundamental physics measurements

et al. 2017

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“…This might be possible using a magnetic fence, consisting of a multipolar magnetic field arrangement similar to the system described in Ref. [72]. For our purpose the multipole of high order has to be oriented such as to provide only field components within the plane defined by the helium surface, i.e., with current-carrying rods parallel to the gravity field.…”

Section: Discussion and Sketches Of Experimental Implementationsmentioning

confidence: 99%

Neutrons on a surface of liquid helium

et al. 2016

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We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyse the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time constant of these UCNs at 0.7 K is found to exceed one hour, and rapidly increasing with decreasing temperature. Such low scattering rates should enable high-precision measurements of the scheme of discrete energy levels, thus providing improved access to short-range gravity. The system might also be useful for neutron β-decay experiments. We also sketch new experimental concepts for level population and trapping of UCNs above a flat horizontal mirror.

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“…In phase II, a magnetic octupole reflector 1 will be added to reduce wall losses in the converter for low-field seeking UCN [19]. This provides in-situ UCN polarization, while also increasing both τ and the maximum UCN energy that can be trapped.…”

Section: Ucn Source: Supersunmentioning

confidence: 99%

The PanEDM neutron electric dipole moment experiment at the ILL

et al. 2019

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The neutron's permanent electric dipole moment d n is constrained to below 3×10 −26 e cm (90% C.L.) [1,2], by experiments using ultracold neutrons (UCN). We plan to improve this limit by an order of magnitude or more with PanEDM, the first experiment exploiting the ILL's new UCN source SuperSUN. SuperSUN is expected to provide a high density of UCN with energies below 80 neV, implying extended statistical reach with respect to existing sources, for experiments that rely on long storage or spin-precession times. Systematic errors in PanEDM are strongly suppressed by passive magnetic shielding, with magnetic field and gradient drifts at the single fT level. A holding-field homogeneity on the order of 10 −4 is achieved in low residual fields, via a high static damping factor and built-in coil system. No comagnetometer is needed for the first orderof-magnitude improvement in d n , thanks to high magnetic stability and an assortment of sensors outside the UCN storage volumes. PanEDM will be commissioned and upgraded in parallel with SuperSUN, to take full advantage of the source's output in each phase. Commissioning is ongoing in 2019, and a new limit in the mid 10 −27 e cm range should be possible with two full reactor cycles of data in the commissioned apparatus.

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Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

Cited by 25 publications

References 87 publications

Comparison of ultracold neutron sources for fundamental physics measurements

Comparison of ultracold neutron sources for fundamental physics measurements

Neutrons on a surface of liquid helium

The PanEDM neutron electric dipole moment experiment at the ILL

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