Ultracold neutron storage and transport at the PSI UCN source.

Efficient neutron transport is a key ingredient to the performance of ultracold neutron (UCN) sources, important to meeting the challenges placed by high precision fundamental physics experiments. At the Paul Scherrer Institute's UCN source we have been continuously improving our understanding of the UCN source parameters by performing a series of studies to characterize neutron production and moderation, and UCN production, extraction, and transport efficiency to the beamport. The present study on the absolute UCN transport efficiency completes our previous publications. We report on complementary measurements, namely one on the height-dependent UCN density and a second on the transmission of a calibrated quantity of UCN over a ∼ 16  m long UCN guide section connecting one beamport via the source storage vessel to another beamport. These allow us quantifying and optimizing the performance of the guide system based on extensive Monte Carlo simulations.

Data blinding for the nEDM experiment at PSI.

Psychological bias towards, or away from, prior measurements or theory predictions is an intrinsic threat to any data analysis. While various methods can be used to try to avoid such a bias, e.g. actively avoiding looking at the result, only data blinding is a traceable and trustworthy method that can circumvent the bias and convince a public audience that there is not even an accidental psychological bias. Data blinding is nowadays a standard practice in particle physics, but it is particularly difficult for experiments searching for the neutron electric dipole moment (nEDM), as several cross measurements, in particular of the magnetic field, create a self-consistent network into which it is hard to inject a false signal. We present an algorithm that modifies the data without influencing the experiment. Results of an automated analysis of the data are used to change the recorded spin state of a few neutrons within each measurement cycle. The flexible algorithm may be applied twice (or more) to the data, thus providing the option of sequentially applying various blinding offsets for separate analysis steps with independent teams. The subtle manner in which the data are modified allows one subsequently to adjust the algorithm and to produce a re-blinded data set without revealing the initial blinding offset. The method was designed for the 2015/2016 measurement campaign of the nEDM experiment at the Paul Scherrer Institute. However, it can be re-used with minor modification for the follow-up experiment n2EDM, and may be suitable for comparable projects elsewhere.

Highly stable atomic vector magnetometer based on free spin precession.

We present a magnetometer based on optically pumped Cs atoms that measures the magnitude and direction of a 1 µT magnetic field. Multiple circularly polarized laser beams were used to probe the free spin precession of the Cs atoms. The design was optimized for long-time stability and achieves a scalar resolution better than 300 fT for integration times ranging from 80 ms to 1000 s. The best scalar resolution of less than 80 fT was reached with integration times of 1.6 to 6 s. We were able to measure the magnetic field direction with a resolution better than 10 µrad for integration times from 10 s up to 2000 s.

Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 µT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1 pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

Achieving ultra-low and -uniform residual magnetic fields in a very large magnetically shielded room for fundamental physics experiments.

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 ∼1.4m3, 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 12h down to 1.5h.

The very large n2EDM magnetically shielded room with an exceptional performance for fundamental physics measurements.

We present the magnetically shielded room (MSR) for the n2EDM experiment at the Paul Scherrer Institute, which features an interior cubic volume with each side of length 2.92 m, thus providing an accessible space of 25 m3. The MSR has 87 openings of diameter up to 220 mm for operating the experimental apparatus inside and an intermediate space between the layers for housing sensitive signal processing electronics. The characterization measurements show a remanent magnetic field in the central 1 m3 below 100 pT and a field below 600 pT in the entire inner volume, up to 4 cm to the walls. The quasi-static shielding factor at 0.01 Hz measured with a sinusoidal 2 µT peak-to-peak signal is about 100 000 in all three spatial directions and increases rapidly with frequency to reach 108 above 1 Hz.

The effect of diabetes mellitus on the lymphatic transport of intestinal sterols.

Previous studies have demonstrated that in intact animals, de novo cholesterol synthesis is increased in the small and large intestines of streptozotocin-induced diabetic rats. The aim of this study was to determine if this enhanced intestinal cholesterol synthesis in diabetic animals results in the increased transport of newly synthesized sterols from the intestines to the peripheral circulation. Thoracic ducts were cannulated in control and diabetic animals and the quantity of newly labeled sterols in the lymph determined after the administration of tritiated water. Labeled sterols in the 24-hour lymph drainage were increased fourfold in the diabetic animals as compared to control animals. Additionally, the percentage of newly synthesized sterols synthesized in the small intestine and transported by the lymph is almost twofold greater in the diabetics. Thus, the increased quantity of labeled sterols present in the thoracic duct lymph of diabetic animals is accounted for by two factors, an enhancement of small intestinal sterol synthesis in diabetic animals and the increased percentage transport of newly synthesized sterols from the small intestine to the bloodstream. In both control and diabetic animals, chylomicrons were the major lipoprotein fraction in which the newly synthesized sterols were transported in the lymph. These findings demonstrate that the increased sterologenesis observed in the intestine of diabetic animals results in the increased transport of newly synthesized cholesterol from the intestines to the circulation.

De novo sterologenesis in the intact rat.

On the basis mainly of in vitro studies, the liver and, to a lesser degree, the small intestine are widely accepted as the major sites of de novo sterologenesis. Utilizing [3H]water, we have investigated de novo sterologenesis in intact rats. Greater than 80% of labeled nonsaponifiable lipids and more than 70% of the labeled cholesterol were localized to extrahepatic, extraintestinal tissues. Feeding cholesterol markedly suppressed hepatic sterologenesis but had little influence on extrahepatic sites of sterol synthesis. Similarly, partial hepatectomy, which greatly decreased sterol synthesis in the liver, also did not significantly affect the accumulation of labeled sterols in extrahepatic tissues; therefore, the transport of sterols from the liver did not account for a significant portion of labeled sterols in extrahepatic tissues. Cannulation of the thoracic duct demonstrated that transport of newly synthesized intestinal sterols to peripheral tissues also did not account for the large accumulation of labeled sterols in extrahepatic, extraintestinal tissues. The primary extrahepatic, extraintestinal sites of sterologenesis were the skin and remaining carcass. The lung, kidney, spleen, heart, ovary, brain, muscle and adipose tissue made minor contributions to de novo sterol synthesis. Therefore, tissues other than the liver and intestine, especially the skin and remaining carcass, are important sites of de novo sterologenesis in vivo.

On the mechanism of polychlorinated biphenyl-induced hypobilirubinaemia.

Treatment of normal rats with a polychlorinated biphenyl mixture of DDT increased liver microsomal protein concentration. Hepatic microsomal bilirubin UDP-glucuronyltransferase activity was elevated in the DDT-treated, but not in the polychlorinated biphenyl-treated rats. In contrast polychlorinated biphenyl, but not DDT, reduced serum bilirubin concentrations in jaundiced Gunn rats, as did sulphadiazine; sulphonamides compete with bilirubin for binding sites on plasma albumin. Polychlorinated biphenyls appear to lower serum bilirubin concentration by reducing the binding of bilirubin to plasma protein.

[Effect of loratadine in children with allergic rhinitis]. / A loratadin hatásai allergiás rhinitisben szenvedö gyermekeknél.

The authors examined 25 children with allergic rhinitis, who were sensitive to grass, weed and tree pollens. During the allergic season nasal lavage was performed then repeated after 4 weeks of loratadine treatment. Tryptase, IL-5, ECP, TNF-alpha and RANTES levels were measured from the nasal lavage fluid. Tryptase, IL-5, and ECP levels were decreased significantly while the decrease of RANTES and TNF-alpha levels was not significant. The authors emphasize that loratadine is an effective anti-inflammatory drug which affects the early and late phase of immediate hypersensitivity. In the moderate cases loratadine is enough to relieve the symptoms, while in the severe forms anti-allergic eye drops and nasal antihistamine or steroid spray has to be added.

[The incidence of iron deficiency in Hungary among children aged 4-6 years]. / A vashiánybetegség gyakorisága Magyarországon a 4-6 éves gyermekek között.

The authors found, that the incidence of hypochromic, microcytic anaemia was 4 percent, and more than half of the children were suffered from iron deficiency. The causes are the inadequate daily iron uptake and/or increase iron requirement. It is very important to increase the iron content of the food and/or the prophylactic or therapeutic iron treatment.

Test of Lorentz invariance with spin precession of ultracold neutrons.

A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and 199Hg atoms, is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron |gn| < 0.3 eV/c2 m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit |gn| < 3 x 10(-4) eV/c2 m.

Cold neutron energy dependent production of ultracold neutrons in solid deuterium.

A measurement of the production of ultracold neutrons from velocity-selected cold neutrons on gaseous and solid deuterium targets is reported. The expected energy dependence for two-particle collisions with well defined neutron and Maxwell-Boltzmann distributed molecular velocities is found for the gas target. The solid target data agree in shape with the phonon density-of-states curve and provide strong evidence for the phonon model including multiphonon excitations.

Direct experimental limit on neutron-mirror-neutron oscillations.

In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron n', could potentially mix and undergo nn' oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the n' amplitude in the n wave function and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and, assuming negligible mirror magnetic fields, a limit on the oscillation time taunn' > 103 s (95% C.L.) is derived.

The effect of portocaval shunt on bile flow and maximal biliary excretion of bromsulfophthalein sodium (BSP) in rats with thioacetamide induced liver cirrhosis.

Thioacetamide (TAA) causes experimental liver cirrhosis in rats. TAA was administered (50 mg per kg body weight i.p. daily) to sham-operated and shunted rats for eight weeks. Then in pentobarbital anesthesia, bile flow and the maximal biliary excretion (Tm) of BSP were measured using constant infusion technique. Compared to the controls, BSP Tm values decreased significantly in cirrhotic rats. The change results from the lower concentration of dye. In cirrhotic animals the liver cannot excrete the dye per net fluid volume as efficiently, as in the controls. In animals having portocaval shunts and liver cirrhosis, a further decrease of dye excretion can be observed, indicating that the operation has some influence on the canalicular excretion of certain organic anions.

Hepatic organic anion transport following portacaval shunt in patients with cirrhosis.

In patients with cirrhosis and bleeding esophageal varices, serum bilirubin level usually increases shortly after portasystemic anastomosis. The aim of the present study was to determine whether a change of the functional reserve capacity of the liver to store or excrete organic anions contributes to this post-shunt hyperbilirubinaemia. For this purpose, the relative hepatic storage capacity (S) and maximal biliary excretory rate (Tm) of bromsulphalein sodium (BSP) were estimated before and after elective portacaval shunts. Studies were performed in 13 cirrhotic patients who received less than 2 units of blood transfusion during the shunt procedure and none afterwards. S and Tm of BSP were determined preoperatively and 4 and 14 days after end-to-side portacaval shunt. Before shunt, S and Tm were significantly less in cirrhotic patients than in individuals with normal liver function. A further decrease of these values occurred 4 days after the shunt, suggesting that the deprivation of portal blood decreased the ability of liver to excrete organic anions. Two weeks postoperatively, S and Tm values were not different from the preoperative data demonstrating a recovery of organic anion transport capacity within a relatively short interval. The present data show that portacaval shunts temporarily reduce the organic anion excretory capacity of the cirrhotic liver. Therefore, large anion load, such as bilirubin derived from increased hemolysis, may temporarily saturate the excretory system, thereby inhibiting the elimination of other, potentially toxic, organic anions.

Bile flow and biliary sulfobromophthalein sodium excretion in rats with liver cirrhosis and portacaval shunt.

In order to study the combined effect of end-to-side portacaval shunt and chronic liver damage on biliary organic anion transport, the rat model of thioacetamide-induced chronic liver injury was utilized. Compared with sham-operated animals, bile flow and maximal biliary excretion (Tm) of sulfobromophthalein sodium (BSP) was decreased in rats 9 weeks after shunt operation. If rats with shunts were treated for 8 weeks with thioacetamide, an agent causing hepatic fibrosis and pseudolobule formation, BSP transport from the hepatocyte into bile was further diminished. Compared with the shunted controls, the thioacetamide-treated rats with shunts had elevated serum bilirubin and alkaline phosphatase concentrations, and on electron microscopy their livers had dilated bile canaliculi with a decreased number of microvilli. Non-shunted rats treated with thioacetamide for 8 weeks had similar but less severe changes in the canalicular ultrastructure. Bile flow and BSP Tm were not influenced by thioacetamide treatment alone, perhaps due to the marked liver hypertrophy in these animals. These results indicate that canalicular active transport of organic anions is more sensitive to the effect of thioacetamide in animals with portacaval shunts than in those with sham operations. A similar impairment of hepatic organic anion handling by hepatotoxic compounds might be the consequence of portasystemic shunts in patients with liver cirrhosis.