Preparation of facilities for fundamental research with ultracold neutrons at PNPI

The WWR-M reactor of PNPI offers a unique opportunity to prepare a source for ultracold neutrons (UCN) in an environment of high neutron flux (about 3*10^12 n/cm^2/s) at still acceptable radiation heat release (about 4*10^-3 W/g). It can be realized within the reactor thermal column situated close to the reactor core. With its large diameter of 1 m, this channel allows to install a 15 cm thick bismuth shielding, a graphite premoderator (300 dm^3 at 20 K), and a superfluid helium converter (35 dm^3). At a temperature of 1.2 K it is possible to remove the heat release power of about 20 W. Using the 4pi flux of cold neutrons within the reactor column can bring more than a factor 100 of cold neutron flux incident on the superfluid helium with respect to the present cold neutron beam conditions at the ILL reactor. The storage lifetime for UCN in superfluid He at 1.2 K is about 30 s, which is sufficient when feeding experiments requiring a similar filling time. The calculated density of UCN with energy between 50 neV and 250 neV in an experimental volume of 40 liters is about 10^4 n/cm^3. Technical solutions for realization of the project are discussed.Comment: 10 pages, more detail

Brane matter, hidden or mirror matter, their various avatars and mixings: many faces of the same physics

Numerous papers deal with the phenomenology related to photon-hidden photon kinetic mixing and with the effects of a mass mixing on particle-hidden particle oscillations. In addition, recent papers underline the existence of a geometrical mixing between branes which would allow a matter swapping between branes. These approaches and their phenomenologies are reminiscent of each other but rely on different physical concepts. In the present paper, we suggest there is no rivalry between these models, which are probably many faces of the same physics. We discuss some phenomenological consequences of a global framework.Comment: 9 pages. Typo corrected. Published in European Physical Journal

Primordial He4 Abundance Constrains the Possible Time Variation of the Higgs Vacuum Expectation Value

We constrain the possible time variation of the Higgs vacuum expectation value ($v$) by recent results on the primordial $^4He$ abundance ($Y_P$). For that, we use an analytic approach which enables us to take important issues into consideration, that have been ignored by previous works, like the $v$-dependence of the relevant cross sections of deuterium production and photodisintegration, including the full Klein- Nishina cross section. Furthermore, we take a non-equilibrium Ansatz for the freeze-out concentration of neutrons and protons and incorporate the latest results on the neutron decay. Finally, we approximate the key-parameters of the primordial $^4He$ production (the mean lifetime of the free neutron and the binding energy of the deuteron) by terms of $v\over v_0$ (where $v_0$ denotes the present theoretical estimate). Eventually, we derive the relation $Y_P \simeq 0.2479 - 5.54 (\frac{v-v_0}{v_0})^2 - 0.808~ (\frac{v-v_0}{v_0})$ and the most stringent limit on a possible time variation of $v$ is given by: $-5.4 \cdot 10^{-4} \leq \frac{v-v_0}{v_0} \leq 4.4 \cdot 10^{-4}$.Comment: Accepted for publication in IJT

DETERMINATION OF BONE DENSITY IN THE GRINDER TEETH AREA

Comparison of bone density among men and women in the area of the proposed dental implantation in the region of the grinder teeth of the upper jaws. In the 21st century, various methods are used to determine bone density in the area of dental implantation; the most common is computer tomography. For a better understanding of computed tomography scans, the dentist uses various computer programs. In our work, we used the Ez3D2009 program of Vatech Co., Ltd. to compare bone density in the area of intended dental implantation in the region of the grinder teeth of men and women. Estimation of bone density in the area of intended dental implantation in the region of the grinder teeth is necessary for the best choice of implants, the progress of the surgical operation, makes it possible to predict more accurately the duration of treatment, ensure reliable fixation and long-term functioning of implants