High-precision searches for an electric dipole moment of the neutron (nEDM) require stable and uniform magnetic field environments. We present the recent achievements of degaussing and equilibrating ...the magnetically shielded room (MSR) for the n2EDM experiment at the Paul Scherrer Institute. We present the final degaussing configuration that will be used for n2EDM after numerous studies. The optimized procedure results in a residual magnetic field that has been reduced by a factor of two. The ultra-low field is achieved with the full magnetic-field-coil system, and a large vacuum vessel installed, both in the MSR. In the inner volume of
∼
1.4
m
3
, the field is now more uniform and below 300 pT. In addition, the procedure is faster and dissipates less heat into the magnetic environment, which in turn, reduces its thermal relaxation time from
12
h
down to
1.5
h
.
We present a novel Active Magnetic Shield (AMS), designed and implemented for the n2EDM experiment at the Paul Scherrer Institute. The experiment will perform a high-sensitivity search for the ...electric dipole moment of the neutron. Magnetic-field stability and control is of key importance for n2EDM. A large, cubic, 5 m side length, magnetically shielded room (MSR) provides a passive, quasi-static shielding-factor of about 105 for its inner sensitive volume. The AMS consists of a system of eight complex, feedback-controlled compensation coils constructed on an irregular grid spanned on a volume of less than 1000 m3 around the MSR. The AMS is designed to provide a stable and uniform magnetic-field environment around the MSR, while being reasonably compact. The system can compensate static and variable magnetic fields up to ±50μT (homogeneous components) and ±5μT/m (first-order gradients), suppressing them to a few μT in the sub-Hertz frequency range. The presented design concept and implementation of the AMS fulfills the requirements of the n2EDM experiment and can be useful for other applications, where magnetically silent environments are important and spatial constraints inhibit simpler geometrical solutions.
Abstract
We report on a search for a new, short-range, spin-dependent interaction using a modified version of the experimental apparatus used to measure the permanent neutron electric dipole moment ...at the Paul Scherrer Institute. This interaction, which could be mediated by axion-like particles, concerned the unpolarized nucleons (protons and neutrons) near the material surfaces of the apparatus and polarized ultracold neutrons stored in vacuum. The dominant systematic uncertainty resulting from magnetic-field gradients was controlled to an unprecedented level of approximately 4 pT cm
−1
using an array of optically-pumped cesium vapor magnetometers and magnetic-field maps independently recorded using a dedicated measurement device. No signature of a theoretically predicted new interaction was found, and we set a new limit on the product of the scalar and the pseudoscalar couplings
g
s
g
p
λ
2
<
8.3
×
10
−
28
m
2
(95% C.L.) in a range of 5
µ
m
<
λ
<
25
mm for the monopole–dipole interaction. This new result confirms and improves our previous limit by a factor of 2.7 and provides the current tightest limit obtained with free neutrons.
We present a novel Active Magnetic Shield (AMS), designed and implemented for the n2EDM experiment at the Paul Scherrer Institute. The experiment will perform a high-sensitivity search for the ...electric dipole moment of the neutron. Magnetic-field stability and control is of key importance for n2EDM. A large, cubic, 5 m side length, magnetically shielded room (MSR) provides a passive, quasi-static shielding-factor of about
10
5
for its inner sensitive volume. The AMS consists of a system of eight complex, feedback-controlled compensation coils constructed on an irregular grid spanned on a volume of less than 1000 m
3
around the MSR. The AMS is designed to provide a stable and uniform magnetic-field environment around the MSR, while being reasonably compact. The system can compensate static and variable magnetic fields up to
±
50
μ
T
(homogeneous components) and
±
5
μ
T/m
(first-order gradients), suppressing them to a few
μ
T
in the sub-Hertz frequency range. The presented design concept and implementation of the AMS fulfills the requirements of the n2EDM experiment and can be useful for other applications, where magnetically silent environments are important and spatial constraints inhibit simpler geometrical solutions.
High-precision searches for an electric dipole moment of the neutron (nEDM)
require stable and uniform magnetic field environments. We present the recent
achievements of degaussing and equilibrating ...the magnetically shielded room
(MSR) for the n2EDM experiment at the Paul Scherrer Institute. We present the
final degaussing configuration that will be used for n2EDM after numerous
studies. The optimized procedure results in a residual magnetic field that has
been reduced by a factor of two. The ultra-low field is achieved with the full
magnetic-field-coil system, and a large vacuum vessel installed, both in the
MSR. In the inner volume of ~1.4 m^3, the field is now more uniform and below
300 pT. In addition, the procedure is faster and dissipates less heat into the
magnetic environment, which in turn, reduces its thermal relaxation time from
12 h down to ~1.5 h.
We present a novel Active Magnetic Shield (AMS), designed and implemented for the n2EDM experiment at the Paul Scherrer Institute. The experiment will perform a high-sensitivity search for the ...electric dipole moment of the neutron. Magnetic-field stability and control is of key importance for n2EDM. A large, cubic, 5m side length, magnetically shielded room (MSR) provides a passive, quasi-static shielding-factor of about 10^5 for its inner sensitive volume. The AMS consists of a system of eight complex, feedback-controlled compensation coils constructed on an irregular grid spanned on a volume of less than 1000m^3 around the MSR. The AMS is designed to provide a stable and uniform magnetic-field environment around the MSR, while being reasonably compact. The system can compensate static and variable magnetic fields up to +-50muT (homogeneous components) and +-5muT (first-order gradients), suppressing them to a few muT in the sub-Hertz frequency range. The presented design concept and implementation of the AMS fulfills the requirements of the n2EDM experiment and can be useful for other applications, where magnetically silent environments are important and spatial constraints inhibit simpler geometrical solutions.
We report on a search for a new, short-range, spin-dependent interaction using a modified version of the experimental apparatus used to measure the permanent neutron electric dipole moment at the ...Paul Scherrer Institute. This interaction, which could be mediated by axion-like particles, concerned the unpolarized nucleons (protons and neutrons) near the material surfaces of the apparatus and polarized ultracold neutrons stored in vacuum. The dominant systematic uncertainty resulting from magnetic-field gradients was controlled to an unprecedented level of approximately 4 pT/cm using an array of optically-pumped cesium vapor magnetometers and magnetic-field maps independently recorded using a dedicated measurement device. No signature of a theoretically predicted new interaction was found, and we set a new limit on the product of the scalar and the pseudoscalar couplings \(g_sg_p\lambda^2 < 8.3 \times 10^{-28}\,\text{m}^2\) (95% C.L.) in a range of \(5\,\mu\text{m} < \lambda < 25\,\text{mm}\) for the monopole-dipole interaction. This new result confirms and improves our previous limit by a factor of 2.7 and provides the current tightest limit obtained with free neutrons.
While the international nEDM collaboration at the Paul Scherrer Institut (PSI) took data in 2017 that covered a considerable fraction of the parameter space of claimed potential signals of ...hypothetical neutron (\(n\)) to mirror-neutron (\(n'\)) transitions, it could not test all claimed signal regions at various mirror magnetic fields. Therefore, a new study of \(n-n'\) oscillations using stored ultracold neutrons (UCNs)is underway at PSI, considerably expanding the reach in parameter space of mirror magnetic fields (\(B'\)) and oscillation time constants (\(\tau_{nn'}\)). The new apparatus is designed to test for the anomalous loss of stored ultracold neutrons as a function of an applied magnetic field. The experiment is distinguished from its predecessors by its very large storage vessel (1.47\,m\(^3\)), enhancing its statistical sensitivity. In a test experiment in 2020 we have demonstrated the capabilities of our apparatus. However, the full analysis of our recent data is still pending. Based on already demonstrated performance, we will reach a sensitivity to oscillation times \(\tau_{nn'}/\sqrt{\cos(\beta)}\) well above hundred seconds, with \(\beta\) being the angle between \(B'\) and the applied magnetic field \(B\). The scan of \(B\) will allow the finding or the comprehensive exclusion of potential signals reported in the analysis of previous experiments and suggested to be consistent with neutron to mirror-neutron oscillations.
Previous research has not sufficiently addressed the availability of geopolymer concrete raw materials, which influences adoption for infrastructure constructions. The overview herein assesses the ...supply, demand, and cost of these raw materials, including fly ash, slag cement, metakaolin, sodium hydroxide, sodium silicate, and silica fume. The results suggest that geopolymer concrete is a viable partial replacement for ordinary Portland cement (OPC) in the United States and Europe. Limitations exist in the rest of world, specifically China. Fly ash-based geopolymer concrete represents an opportunity due to low cost along with significant global production and reserves. Additionally, an activating solution composed of sodium hydroxide and silica fume with 25% Portland cement as a partial replacement appears to be most desirable. However, approximately only 7% replacement of OPC with geopolymer concrete is currently feasible globally due to limitations in sodium hydroxide supply. The analysis reveals a need for continued research to reduce the use of sodium hydroxide to improve availability and reduce cost of geopolymer concrete.
•Recommend preferred geopolymer concrete mixture based on performance and supply.•Sodium hydroxide supply restricts geopolymer concrete to 7% global concrete demand.•Estimated 75% (US), 100% (Europe) concrete demand can be met by geopolymer concrete.•Less than 0.50% concrete demand in China can be met by geopolymer concrete.
Research has shown that alkali-activated concrete (AAC) is comparable to ordinary Portland cement concrete (OPCC) in terms of mechanical properties and may offer ecological benefits compared to OPCC. ...This study evaluates the energy and emission of AAC and OPCC across different classifications of concrete compressive strength (40, 60, and 100 MPa). Analysis indicates that the selection of constituent materials can substantially affect the energy and emission of AAC and OPCC. Ordinary Portland cement (OPC) is the principal contributor to the energy and emission of OPCC, accounting for 80% of energy and 91% of emissions of OPCC. The activating solution, meanwhile, is the main contributor to the energy and CO2 emission of AAC. Normal strength AAC (40 MPa) shows 46% less energy and 73% less CO2 emission than OPCC. However, high-strength AAC (60 MPa), using metakaolin as a base material, experiences higher energy (8%) than OPCC yet the emission is 40% less than OPCC. A substitution of fly ash for metakaolin results in superior efficiency of AAC compared to OPCC. Two mixtures of ultra-high-strength AAC (100 MPa) result in contradictory findings. One mixture with a sodium hydroxide and silica fume activating solution shows 5% and 30% less energy and CO2 emission, while the other mixture with a sodium hydroxide and sodium silicate activating mixture is less efficient than OPCC.
•AAC of grade 40 MPa shows 46% and 73% less energy and CO2 emission than OPCC counterpart.-•AAC of grade 60 MPa experiences 8% higher energy than OPCC yet the emission is 40% less.•Attention should be paid to activating solution ingredients to control energy and CO2 emission.•Sodium hydroxide and sodium silicate concentrations have a fatal effect on embodied energy and CO2 emissions of AAC.
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