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Abstract: Absorber materials for low-energy neutrons are studied in the theoretical framework of quantum mechanics with a complex potential. Analytical expressions and numerical calculations of the neutron reflectivity for perpendicular and isotropic motion towards a surface for four different material classes are presented. Comparative experimental studies of four absorber materials have been carried out: Polyethylene, titanium, boron-10 and lithium stearate. In a quasi-storage experiment with ultracold neutrons the latter material features the highest absorption property. [Copyright &y& Elsevier]

Abstract: We report on the design and construction of an efficient gravitational spectrometer for ultracold neutrons. The spectrometer is suited to experiments that can greatly profit from knowledge of the neutron energy spectrum without losing available statistics, such as many of the current precision experiments that use ultracold neutrons. The description of the apparatus is complemented by the results of the first test measurements which served as a proof of principle and showed its capability of discriminating between different UCN energy ranges. The measurements showed the expected behavior and are in qualitative agreement with Monte Carlo simulations. [Copyright &y& Elsevier]

Abstract: We describe a neutron gravity quantum experiment of a new type. The gain in kinetic energy of free-falling neutrons is compensated by a quantum of energy , due to phase modulation of the neutron wave. As phase modulator a grating was used moving perpendicular with respect to the direction of the neutron wave propagation. As a result, monochromatic neutrons will have exactly the same energy after falling as before the free fall. The weak equivalence principle was tested to an accuracy of 2×10−3. A possible future experiment of more improved accuracy is discussed as well. [Copyright &y& Elsevier]

Abstract: A PNPI/ILL experiment to measure the neutron electric dipole moment (EDM) is currently being prepared at the facility PF2 for ultracold neutrons (UCN) at the Institut Laue-Langevin in Grenoble. To enable an improvement of sensitivity, one of PF2''s beam positions has been equipped with new components for UCN transport, polarization and beam characterization, comprised of a superconducting solenoid-polarizer with magnetic field 4T, a neutron guide system with diameter 136mm prepared in replica technology, and a novel beam chopper for time-of-flight analysis. The whole EDM apparatus is set up on a non-magnetic platform. The total flux of polarized UCN with velocities less than 6.8m/s along the guide axis is 1.5×105 n/s, corresponding to a flux density of 103 cm−2 s−1. The density of polarized UCN at the experimental position is about 5cm−3, which shall lead to an EDM measurement with a counting statistical accuracy of 1.5×10−26 ecm during 200 days of operation at PF2. [Copyright &y& Elsevier]

Abstract: We report the design and test of a compact, large-diameter spinflipper for ultracold neutrons based on the principle of adiabatic spinflip. A solenoid rf coil with a high diameter-to-length ratio (d/l~1.7) is surrounded by up to three short magnet coils (d/l~0.4…1.7) to provide the static gradient field. The device is optimized for low power consumption and operation in high vacuum. The magnetic field conditions necessary for full spinflipper efficiency over the full diameter were evaluated with ultracold neutrons. The measured spinflipper efficiency vs. adiabaticity correlation is in good agreement with a calculation based on an ideally linear gradient. [Copyright &y& Elsevier]

Abstract: The reflectivity of ultracold neutron (UCN) guides produced with a dedicated technique called Replika has been studied. The guides are made of nickel, where the surface quality was copied from a glass layer. This results in a surface roughness smaller than 10Å. The reflectivity was measured to be 99.9(1)%. Those guides can be used at present or future UCN sources to transport UCN over long distances to the respective experiments without significant losses. [Copyright &y& Elsevier]

We have measured the transmission of ultra-cold neutrons (UCN) through tubes coated on the inside with materials of high optical potentials. The best transmission value, T, normalised to 1m long UCN guides was obtained with a beryllium coated quartz guide, T=(99.0±1.0)%. Furthermore, excellent transmission coefficients were found for (i) a glass tube coated with NiMo(88/12), T=(97.3 ±0.6)%, (ii) a NiMo(85/15) guide made by the replication technique, T=(97.1 ±0.8)% and (iii) a glass guide coated with NiMo(82/18), T=(96.3 ±2.1)%. The results demonstrate that UCN guides made from coated glass tubes have the same excellent transmission properties as those produced with the replication technique. They are, however, significantly cheaper. [ABSTRACT FROM AUTHOR]

Abstract: We have built a device to filter ultracold neutrons with axial velocities from faster neutrons. The apparatus has been successfully tested at the Institut Laue-Langevin in Grenoble and is used in specific experiments, e.g., the measurement of ultracold neutron transmission through various types of neutron guides. [Copyright &y& Elsevier]

Abstract: A position sensitive detector for ultra-cold neutrons (UCNs) has been developed. Here we present the first experimental results and compare them with Monte-Carlo simulations. The silicon pixel device “TimePix” with a spatial resolution below 1μm for strongly ionizing particles has been coated with a conversion layer of 6LiF for the detection of UCN. A spatial resolution of 5.3μm has been measured for UCN. An optimized setup with 10B as conversion layer can achieve a spatial resolution below 3μm. [Copyright &y& Elsevier]

Abstract: A method for evaluating the properties of guides for ultracold neutrons (UCN) has been developed as an extension of the common technique for measuring UCN losses in the sample contained between two diaphragms. With two measurements at both ends of the guide one can evaluate both, the loss probability per wall collision and the probability f for diffuse scattering from the wall. A 3.4m long aluminum tube coated with a double layer of stainless steel (thickness 500nm) and beryllium (thickness 250nm), proposed as a UCN guide for the Mini-D2 UCN source at the FRM-II reactor at Garching, was tested. We obtained and . Systematic errors and a possible improvement of the method are discussed. [Copyright &y& Elsevier]

Abstract: We propose to measure the neutron lifetime in a complex experiment using storage of ultracold neutrons in two traps with significantly different mean free path. The trap walls are coated with a low-temperature liquid fluorine polymer. Known possible systematic false effects will be largely reduced compared to those in preceding experiments due to corresponding setup design and measuring procedure. [Copyright &y& Elsevier]

Abstract: We present a first experimental demonstration of a new method to extract a collimated beam of ultra-cold neutrons (UCN) from a storage vessel. Neutrons with too large divergence are not removed from the beam by an absorbing collimation, but a diffuse or semidiffuse channel with high Fermi potential reflects them back into the vessel. This avoids unnecessary losses and keeps the storage time high, which may be beneficial when the vessel is part of a UCN source with long buildup time of a high UCN density. [Copyright &y& Elsevier]

Abstract Nanocomposites enable us to tune parameters that are crucial for use of such materials for neutron-optics applications. By careful choice of properties such as species (isotope) and concentration of contained nanoparticles, diffractive optical elements for long-wavelength neutrons are feasible. Nanocomposites for neutron optics have so far been tested successfully in protonated form, containing high amounts of 1 H atoms, which exhibits rather strong neutron absorption and incoherent scattering. At a future stage of development, chemicals containing 1H could be replaced by components containing more favorable isotopes, such as 2 H or 19F. In this note, we present results of Monte-Carlo simulations of the transmissivity of various nanocomposite materials for thermal and very-cold neutron spectra. Our simulation results for deuterated and fluorinated nanocomposite materials predict the losses due to absorption and scattering to be as low as 2%, as well as the broadening of the beam cross section to be negligible. [ABSTRACT FROM AUTHOR]

High spatial resolution of ultracold neutron (UCN) measurement is of growing interest to UCN experiments such as UCN spectrometers, UCN polarimeters, quantum physics of UCNs, and quantum gravity. Here we utilize physics-informed deep learning to enhance the experimental position resolution and to demonstrate sub-micron spatial resolutions for UCN position measurements obtained using a room-temperature CMOS sensor, extending our previous work (Kuk et al., 2021; Yue et al., 2023) that demonstrated a position uncertainty of 1. 5 μ m. We explore the use of the open-source software Allpix Squared to generate experiment-like synthetic hit images with ground-truth position labels. We use physics-informed deep learning by training a fully-connected neural network (FCNN) to learn a mapping from input hit images to output hit position. The automated analysis for sub-micron position resolution in UCN detection combined with the fast data rates of current and next generation UCN sources will enable improved precision for future UCN research and applications. [ABSTRACT FROM AUTHOR]

We report on the evaluation of commercial electroless nickel phosphorus (NiP) coatings for ultracold neutron (UCN) transport and storage. The material potential of 50 μ m thick NiP coatings on stainless steel and aluminum substrates was measured to be V F = 213 ( 5 . 2 ) neV using the time-of-flight spectrometer ASTERIX at the Lujan Center. The loss per bounce probability was measured in pinhole bottling experiments carried out at ultracold neutron sources at Los Alamos Neutron Science Center and the Institut Laue-Langevin. For these tests a new guide coupling design was used to minimize gaps between the guide sections. The observed UCN loss in the bottle was interpreted in terms of an energy independent effective loss per bounce, which is the appropriate model when gaps in the system and upscattering are the dominate loss mechanisms, yielding a loss per bounce of 1 . 3 ( 1 ) × 1 0 − 4 . We also present a detailed discussion of the pinhole bottling methodology and an energy dependent analysis of the experimental results. [ABSTRACT FROM AUTHOR]

We report the first experimental test of TOF-MIEZE technique using very cold neutrons (VCNs) towards high-resolution quasi-elastic neutron scattering spectroscopy. TOF-MIEZE is a type of neutron resonance spin echo spectroscopy with a combination of the time-of-flight (TOF) method and modulation of intensity by zero effort (MIEZE). A compact MIEZE instrument was constructed at the VCN beam port at the High Flux Reactor at the Institut Laue Langevin. By accumulating individual oscillations of raw data, we observed a TOF-MIEZE signal with an effective frequency of 50 kHz in a wavelength band of 4–6 nm. The signal contrasts were 0.59 ± 0.04 and 0.29 ± 0.03 for wavelengths of 4 nm and 6 nm, respectively. The Fourier time was estimated to be 70 ns with 6 nm VCNs in the experimental set-up. [ABSTRACT FROM AUTHOR]

Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15 μ m has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δ E = m 0 g δ x . Here, the symbols δ E , δ x , m 0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. This method allows different types of UCN spectroscopy and other applications. [ABSTRACT FROM AUTHOR]

We describe a new time-of-flight Fourier spectrometer for investigation of UCN diffraction by a moving grating. The device operates in the regime of a discrete set of modulation frequencies. The results of the first experiments show that the spectrometer may be used for obtaining UCN energy spectra in the energy range of 60 – 200 neV with a resolution of about 5 neV. The accuracy of determination of the line position was estimated to be several units of 10 −10 eV. [ABSTRACT FROM AUTHOR]

There are worldwide efforts to search for physics beyond the Standard Model of particle physics. Precision experiments using ultracold neutrons (UCN) require very high intensities of UCN. Efficient transport of UCN from the production volume to the experiment is therefore of great importance. We have developed a method using prestored UCN in order to quantify UCN transmission in tubular guides. This method simulates the final installation at the Paul Scherrer Institute׳s UCN source where neutrons are stored in an intermediate storage vessel serving three experimental ports. This method allowed us to qualify UCN guides for their intended use and compare their properties. [ABSTRACT FROM AUTHOR]

We describe an experimental installation for a new test of the weak equivalence principle for neutron. The device is a sensitive gravitational spectrometer for ultracold neutrons allowing to precisely compare the gain in kinetic energy of free falling neutrons to quanta of energy ℏ Ω transferred to the neutron via a non stationary device, i.e. a quantum modulator. The results of first test experiments indicate a collection rate allowing measurements of the factor of equivalence γ with a statistical uncertainty in the order of 5×10 −3 per day. A number of systematic effects were found, which partially can be easily corrected. For the elimination of others more detailed investigations and analysis are needed. Some possibilities to improve the device are also discussed. [ABSTRACT FROM AUTHOR]

We present an improved instrument for the determination of the neutron electric charge with ultracold neutrons. Several technical upgrades with respect to a former experiment will be discussed in detail. As a first test, we applied the apparatus to investigate the influence of gravitational attraction by means of a massive block of lead. The calculated sensitivity for a charge measurement is δ q n ≈ 2.14 × 10 − 20 e / day . Planned modifications increasing the sensitivity up to δ q n ≈ 1.34 × 10 − 21 e / day are demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: A description is presented of apparatus used to carry out an experimental search for an electric dipole moment of the neutron, at the Institut Laue-Langevin (ILL), Grenoble. The experiment incorporated a cohabiting atomic-mercury magnetometer in order to reduce spurious signals from magnetic field fluctuations. The result has been published in an earlier letter [1]; here, the methods and equipment used are discussed in detail. [Copyright &y& Elsevier]

Abstract: We developed an optical device for ultra-cold neutrons and investigated the influence of a tilt of its guiding components. A measurement of the time-of-flight of the neutrons through the device by means of a dedicated chopper system was performed and a light-optical method for the alignment of the guiding components is demonstrated. A comparative analysis of former experiments with our results shows the potential of such a device to test the electrical neutrality of the free neutron on the 10−22 q e level and to investigate the interaction of neutrons with gravity. [Copyright &y& Elsevier]

Abstract: The efficient transport of ultra-cold neutrons (UCN) from their source to the experimental site is a major issue for various kinds of precision experiments. Neutron guides often have to transport the UCN several tens of meters with acceptable losses. In order to qualify the guides, their UCN transmission properties have to be determined with high precision. For this purpose we have developed a novel method. The transmitted UCN were absorbed at the end of the guide in a vanadium disc producing the β-emitter 52 V (half life 3.74min). The intensity of the 1434keV γ-ray following the β-decay was measured. UCN guides of non-magnetic nickel alloys made by the replication technique were studied. They show a high Fermi pseudopotential V F for UCN and a low surface roughness. For these guides the transmission per meter was determined with a relative error of ±0.6%, resulting in values above 0.95/m. By an absolute calibration of the γ-ray detection system we also deduced the absolute value of the UCN current absorbed in the vanadium plate. Possible applications of this method are discussed. [Copyright &y& Elsevier]

Abstract: Marginally trapped neutrons are a major source of systematic errors in storage experiments with ultra-cold neutrons (UCN): their energies slightly exceed the trapping potential and their storage lifetimes are of the same order of magnitude as the neutron -decay lifetime to be measured. Hence, they have to be removed before the actual neutron storage period starts. For the magneto-gravitational neutron-lifetime experiment PENeLOPE, a novel absorber scheme was proposed; its efficiency to reduce the systematic influence of marginally trapped UCN on the extracted -decay lifetime value had to be investigated. To this end, the cryogenic material-storage experiment AbEx (Ab sorber Ex periment) was conducted at ILL, Grenoble; neutron-optical properties of storage and absorption materials were investigated. Storage lifetimes shorter than 10s could be reached for high-energy UCN with the proposed scheme. This translates to a systematic effect on the neutron-lifetime measurement with PENeLOPE of . Polyethylene (PE) and titanium were tested as absorber materials. The temperature dependence of their UCN absorbing efficiency was determined to be rather small and connected not with the upscattering cross-section, but probably with surface contaminations. [Copyright &y& Elsevier]

Abstract: We present the status of an experimental setup designed and built for the measurement of the neutron lifetime and we describe also details about the measuring sequence. The central element of the setup is a magnetic trap made of permanent magnets. Neutrons surviving in the trap after fixed storage times are counted after their extraction and the trap losses are continuously monitored during the storage periods. The technique has achieved a statistical sensitivity of about 2s on the storage time what constitutes the most sensitive magnetic trapping technique for ultra-cold neutrons developed so far. [Copyright &y& Elsevier]

Abstract: We have investigated the properties of the ultracold neutron converter materials deuterium , oxygen and heavy methane in the temperature range between 8K and room temperature. The experimental program was performed at the FUNSPIN beamline of the Swiss Spallation Neutron Source (SINQ) at Paul Scherrer Institut (PSI). In this paper the measured cold neutron total cross-sections for , and are presented. [Copyright &y& Elsevier]

Abstract: Mirror matter is considered as a candidate for dark matter. In connection with this an experimental search for neutron–mirror neutron (nn′) transitions has been carried out using storage of ultracold neutrons in a trap with different magnetic fields. As a result, a new limit for the neutron–mirror neutron oscillation time τ osc has been obtained, τ osc≥448s (90% C.L.), assuming that there is no mirror magnetic field larger than 100nT. Besides a first attempt to obtain some restriction for mirror magnetic field has been done. [Copyright &y& Elsevier]

Abstract: At the Paul Scherrer Institute (PSI), a very intense source of ultracold neutrons (UCN) is being built. The UCN converter of solid deuterium must be contained in a vessel. Produced UCN leave that vessel through its top lid. To decide on the design of the vessel and the top lid, we have measured the transmission of neutrons with velocities between 3 and 20m/s through different material foils. Contrary to expectations, we found that transmission through aluminium and aluminium alloys is equal or even higher compared to zirconium and reactor-grade zirconium alloys, respectively. [Copyright &y& Elsevier]

Abstract: We have fabricated ultracold neutron detectors that consist of silicon charged particle detectors coupled with thin nickel foils coated with either natural LiF or 10B implanted into vanadium. The foils convert neutrons into energetic, readily detectable, charged particles which are in turn detected by silicon detectors. The detectors were tested at the Institut Laue-Langevin with a gravitational spectrometer. From a rigorous Monte Carlo simulation of the experiment, the minimum detection cutoff velocities (effective potentials) were determined to be () for LiF and () for 10B/V. Although the result for LiF is consistent with expectations, the result for 10B/V is significantly higher. We interpret this discrepancy as due to contamination. We also show that while a thicker foil is more efficient for ultracold neutron detection, a thinner foil is more ideal for determining the cutoff velocity. [Copyright &y& Elsevier]

Abstract: Neutrons are particularly useful to study the evolution of a genuine spin- quantum system and its interaction with the environment. We report on the characteristics of a newly designed apparatus for storing ultra-cold neutrons (UCN) and manipulating their spin by means of a 3D Helmholtz-coil arrangement. In particular, using UCN requires homogeneous and stable magnetic fields across the storage volume in order to maintain a spin-superposition state for a sufficiently long time. Experimental results on the successful manipulation of the neutrons spin by means of Rabi oscillations and Ramsey interference fringes with a newly designed apparatus are presented. Coherence times exceeding make the apparatus suitable for further measurements on (de-)coherence and geometric phases. [Copyright &y& Elsevier]

Abstract: We describe the production, characterization and performance of magnetron-sputtered Be coatings on aluminum, copper and stainless steel substrates. The coating thickness is typically 300nm. Small samples were characterized by means of Optical Microscopy (OM), Atomic Force Microscopy (AFM) and X-ray induced Photoelectron Spectroscopy (XPS) and Elastic Recoil Detection Analysis (ERDA). The coating quality and adhesion following thermal cycling and neutron irradiation were tested with respect to future applications as storage containers in Ultracold Neutron (UCN) sources. The fractional uncoated area was determined to be 10−4 to 10−5 by OM and XPS. These results were confirmed by foil transmission measurements with UCN in the energy range 180 to 230neV. The storage time of a 250l Be-coated Cu container was determined for UCN energies up to 60neV at room temperature and around 90K and the wall loss factor η extracted. We obtained η (90K)=2.7×10−5 and η(300K)=1.1×10−4 in good agreement with previously published results. [Copyright &y& Elsevier]

Abstract: We have built a novel apparatus for the investigation of materials for the storage of ultracold neutrons. Neutrons are filled into a storage volume, confined at the bottom by a magnetic field, at the top by gravity and at the sides by the slit-less sample surface under investigation. For different beryllium and diamond-like carbon samples, storage times up to 200s were obtained at room temperature. The corresponding loss parameters for ultracold neutrons varied between 4.2 and per wall collision. [Copyright &y& Elsevier]

Abstract: A silicon UCN detector with an area of and with a converter was developed at PNPI. The spectral efficiency of the silicon UCN detector was measured by means of a gravitational spectrometer at ILL. The sandwich-type detector from two silicon plates with a converter placed between them was also studied. Using this type of technology the UCN detector with analysis of polarization was developed and tested. The analyzing power of this detector assembly reaches up to 75% for the main part of UCN spectrum. This UCN detector with analysis of UCN polarization can be used in the new EDM spectrometer. [Copyright &y& Elsevier]

Abstract: Low-energy neutron radiographic images of Hedera leaves were obtained using the very cold neutron (VCN) beam at Institut Laue-Langevin, France. A change in hydrogen concentration measured in a short period by means of neutron radiography indicates a change in water concentration in the plant. A regression model was evaluated to estimate changes in water thickness of the leaves and, the resolution of this method was smaller than 5μm. The method was effective to measure small changes in water thickness of thin plant leaves. [Copyright &y& Elsevier]

Abstract: Solid deuterium (sD) is a favourite converter material for the production of ultra-cold neutrons (UCN) in the next generation of UCN sources. In order to investigate sD properties relevant for this purpose, an apparatus for the preparation and characterization of ortho-D crystals has been built. It will be used for measurements of neutron transmission and scattering cross-sections as well as irradiation experiments with simultaneous optical control of the target conditions. The present paper describes the main components of the apparatus, i.e. the cryogenic optical D cell, the gas system, the optical photography system and the Raman spectroscopy system. [Copyright &y& Elsevier]

Solid ultra-cold neutron detectors consisting of a neutron converter layer and a silicon pin-diode were tested at Institute Laue Langevin. Two kinds of converter, LiF and LiOH, were used, and their critical velocities covered the range from 0.8 to 5.0 m/s by adjusting the isotopic fraction of 6Li in Li. All tested detectors measured the UCN below their critical velocities down to 1.5 m/s without a clear cutoff feature at their critical velocities. It is an abnormal absorption of UCN. It was also observed that the detector efficiencies of all tested detectors approach together in the UCN region, 4–6 m/s, in spite of the variety of critical velocity and thickness of converters. [Copyright &y& Elsevier]

As part of an R&D programme for the development of a next-generation experiment to measure the neutron electric dipole moment, in which ultra-cold neutrons (UCN) are produced and stored in superfluid 4He (superthermal source), we have developed cryogenic detectors of UCN that can operate in situ within the superfluid. Surface barrier detectors and PIN diode detectors have been tested and proven to work well at temperatures as low as 80 mK. When combined with a layer of 6LiF which converts neutrons to charged particles, these detectors form a reliable UCN detection system which has been tested in liquid helium down to 430 mK. The detectors have operated within superfluid helium for periods of up to 30 days with no signs of degradation. The development of this detection system has enabled us to measure the flux of UCN from a superthermal UCN source with no intervening transmission windows which can attenuate the flux. The addition of thin films of magnetically aligned iron also enables these detectors to be used in situ for neutron spin-polarisation analysis. [Copyright &y& Elsevier]

The 39Ar(nth,α)36S reaction has been studied for the first time. A sample containing 2.85×1014 39Ar atoms was produced at the ISOLDE facility at CERN. The number of 39Ar atoms in the layer was determined by measuring the 39Ar β-activity using a primary standardisation method. Subsequently, the sample was irradiated with thermal neutrons at the High Flux Reactor of the Institut Laue–Langevin. An upper limit of 0.29b was obtained for the 39Ar(nth,α)36S reaction cross-section. [Copyright &y& Elsevier]

We present a study aimed at developing and optimising methods for ultra-cold neutron (UCN) detection using solid-state silicon detectors. For this we investigated the characteristics of neutron to charged particle converters (6Li, 10B) and compared different deposition techniques. We find that a deposition of 600 μg/cm2 of 6LiF is required to ensure maximum UCN detection efficiency using 6Li as converter. The UCN detectors that we have developed are now fully operational as a flux monitor and as a UCN spectrum analyser in the neutron electric dipole moment experiment at the Institut Laue Langevin in Grenoble. [Copyright &y& Elsevier]

Abstract: We present an implementation of the silicon pixel device Timepix for position and energy-sensitive detection of ultra-cold neutrons (UCN) with an efficiency of 70% and a spatial resolution of 5.3μm. A layer of 400μg/cm2 of 6LiF deposited onto the Timepix sensor surface was used as a neutron converter. The energy of each detected neutron is measured using standard time-of-flight (TOF) technique. Thus, for each detected neutron the position and energy is determined. We demonstrate this technique on the real-time measurement of energy- and position-dependent reflection of UCNs from a bent foil of stainless steel making direct visualization of total reflection angle for different neutron energies. [Copyright &y& Elsevier]

Abstract: A test experiment has shown that the number of ultra cold neutrons (UCN) of one polarization transmitted through a 100 μm Al foil when placed in a 5T magnetic field is greater by 3.8 times. The increased transmission is due to a higher velocity of the UCN passing through the foil. [Copyright &y& Elsevier]

Abstract: We have developed a prototype rotating-permanent magnet sextupole lens (named rot-PMSx) for more efficient experiments with neutron beams in time of flight (ToF) mode. This lens can modulate the focusing strength over range . Synchronization between the modulation and the beam pulse produces a focused beam without significant chromatic aberration. We anticipate that this lens could be utilized in focusing small angle neutron scattering (SANS) instruments for novel approach to high resolution SANS. We carried out experiments testing the principle of this lens at the very cold neutron (VCN) beamline (PF2) at Institut Laue-Langevin (ILL), France. The focused beam image size at the detector was kept constant at the same beam size as the source over a wavelength range of in focal length of . The flux gain was about 12 relative to a beam without focusing, and the depth of focus was quite large. These results show the good performance of this lens and the system. Thereupon we have demonstrated the performance of this test bed for high resolution focusing of VCN-SANS for a well-studied softmatter sample; a deuterium oxide solution of Pluronic F127, an (PEO)100(PPO)65(PEO)100 tri-block copolymer in deuterium oxide. The results of the focusing experiment and the focusing VCN-SANS are presented. [Copyright &y& Elsevier]

Abstract: The preparation of intercalated graphite compounds is now well established at the Institut Laue Langevin (ILL). We are able to manufacture several types of intercalated crystals, such as KC8, RbC8, KC24 and RbC24 compounds, in large quantities and in a reproducible manner. Even though the mosaic distribution is large, these compounds exhibit a high neutron peak reflectivity of about 70% at a neutron wavelength of 9.8Å. The production of such intercalated graphite crystals allows us to build efficient neutron monochromators for wavelengths in the range 6–15Å. [Copyright &y& Elsevier]