Bremsstrahlung emission during α\alpha-decay of 226Ra^{226}{\rm Ra}

We obtained the spectrum of probability of the bremsstrahlung emission accompanying the $\alpha$-decay of $^{226}{\rm Ra}$ (E$_{\alpha}$=4.8 MeV) by measuring the $\alpha$-$\gamma$ coincidences and using the model presented in our previous study on the $\alpha-$decay of $^{214}{\rm Po}$ (E$_{\alpha}$=7.7 MeV). We compare the experimental data with the quantum mechanical calculation and find a good agreement between theory and experiment. We discuss the differences between the photon spectra connected with the $\alpha$-decay of the $^{226}{\rm Ra}$ and $^{214}{\rm Po}$ nuclei. For the two mentioned nuclei we analyze the bremsstrahlung emission contributions from the tunneling and external regions of the nucleus barrier into the total spectrum, and we find the destructive interference between these contributions. We also find that the emission of photons during tunneling of the $\alpha$-particle gives an important contribution to the bremsstrahlung spectrum in the whole E$_{\gamma}$ energy range of the studied $^{226}$Ra nucleus

Comparative evaluation of the clinical efficacy and safety of surgical approaches in total hip arthroplasty

Background Advanced coxarthrosis is a leading cause of disability in patients. Total arthroplasty is regarded as the "gold standard" for the treatment of hip pathologies that are not amenable to conservative treatment. Arthroplasty introduced into clinical practice has significantly improved functional status of patients. The data are largely contradictory and indicate certain difficulties and risks at the stages of treatment and rehabilitation of patients after surgery. The shortcomings can be overcome by improving the treatment methods for the cohort of patients based on the results of large-scale comparative studies exploring the effectiveness of different approaches to all stages of treatment of arthroplastic patients. The objective was to search for the most justified and promising surgical approaches in terms of clinical efficacy and safety of total hip arthroplasty (THA). Material and methods The search for publications was produced using the databases of Scopus, PubMed and the electronic scientific library eLIBRARY in Russian and English languages using the keywords: total hip arthroplasty, minimally invasive approach, anterolateral approach in THA, direct lateral approach in THA, posterior approach in THA, comparative assessment of approaches in hip arthroplasty, advanced replacement techniques, incidence of postoperative complications in THA, direct anterior approach in THA. Results and discussion A number of studies have shown that interventions using direct anterior access (DAA) are characterized by less blood loss, less frequent blood transfusions, less operating time and shorter hospital stay. There was a more rapid recovery of the hip function during early postoperative period with less need for opioid analgesics with DAA. Complication rate was higher with DAA than in the comparison group, which directly correlated with the learning curve. Conclusion DAA was shown to be an advanced approach that resulted in enhanced clinical efficacy and safety of surgical treatment in the majority of patients with coxarthrosis with sufficient experience of the surgeon. The method can be considered as low-traumatic. Unlike other approaches, DAA was accompanied by less injury to intact tissues; smaller skin incision; less blood loss; precipitated postoperative rehabilitation; less severity of postoperative pain and less need for opioid analgesia. However, DAA is inferior to classical approaches in primarily complicated hip pathologies

Interphase REE Partitioning at the Boundary between the Earth’s Transition Zone and Lower Mantle: Evidence from Experiments and Atomistic Modeling

Trace elements play a significant role in interpretation of different processes in the deep Earth. However, the systematics of interphase rare-earth element (REE) partitioning under the conditions of the uppermost lower mantle are poorly understood. We performed high-pressure experiments to study the phase relations in key solid-phase reactions CaMgSi2O6 = CaSiO3-perovskite + MgSiO3-bridgmanite and (Mg,Fe)2SiO4-ringwoodite = (Mg,Fe)SiO3-bridgmanite + (Mg,Fe)O with addition of 1 wt % of REE oxides. Atomistic modeling was used to obtain more accurate quantitative estimates of the interphase REE partitioning and displayed the ideal model for the high-pressure minerals. HREE (Er, Tm, Yb, and Lu) are mostly accumulated in bridgmanite, while LREE are predominantly redistributed into CaSiO3. On the basis of the results of experiments and atomistic modeling, REE in bridgmanite are clearly divided into two groups (from La to Gd and from Gd to Lu). Interphase REE partition coefficients in solid-state reactions were calculated at 21.5 and 24 GPa for the first time. The new data are applicable for interpretation of the trace-element composition of the lower mantle inclusions in natural diamonds from kimberlite; the experimentally determined effect of pressure on the interphase (bridgmanite/CaSiO3-perovskite) REE partition coefficients can be a potential qualitative geobarometer for mineral inclusions in super-deep diamonds

Measurement of pseudorapidity distributions of charged particles in proton-proton collisions at sqrt(s) = 8 TeV by the CMS and TOTEM experiments

Pseudorapidity ( $\eta$ ) distributions of charged particles produced in proton–proton collisions at a centre-of-mass energy of 8 $~\text {TeV}$ are measured in the ranges $|\eta | < 2.2$ and $5.3 < |\eta | < 6.4$ covered by the CMS and TOTEM detectors, respectively. The data correspond to an integrated luminosity of $\mathcal {L} = 45 \mu {\mathrm {b}}^{-1}$ . Measurements are presented for three event categories. The most inclusive category is sensitive to 91–96 % of the total inelastic proton–proton cross section. The other two categories are disjoint subsets of the inclusive sample that are either enhanced or depleted in single diffractive dissociation events. The data are compared to models used to describe high-energy hadronic interactions. None of the models considered provide a consistent description of the measured distributions

First search for exclusive diphoton production at high mass with tagged protons in proton-proton collisions at s=\sqrt{s} = 13 TeV

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp $\to$ p$\gamma\gamma$p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb$^{-1}$ collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeV at the LHC. Events are selected with a diphoton invariant mass above 350 GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons matches the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% CL are $\lvert\zeta_1\rvert$ $\lt$ 2.9 $\times$ 10$^{-13}$ GeV$^{-4}$ and $\lvert\zeta_2\rvert$ $\lt$ 6.0 $\times$ 10$^{-13}$ GeV$^{-4}$

Measurement of single-diffractive dijet production in proton-proton collisions at s=\sqrt{s} =s​= 8 TeV with the CMS and TOTEM experiments

Measurements are presented of the single-diffractive dijet cross section and the diffractive cross section as a function of the proton fractional momentum loss $\xi$ and the four-momentum transfer squared t. Both processes ${\text{ p }{}{}} {\text{ p }{}{}} \rightarrow {\text{ p }{}{}} {\text{ X }}$ and ${\text{ p }{}{}} {\text{ p }{}{}} \rightarrow {\text{ X }} {\text{ p }{}{}}$, i.e. with the proton scattering to either side of the interaction point, are measured, where ${\text{ X }}$ includes at least two jets; the results of the two processes are averaged. The analyses are based on data collected simultaneously with the CMS and TOTEM detectors at the LHC in proton–proton collisions at $\sqrt{s} = 8\,\text {Te}\text {V}$ during a dedicated run with $\beta ^{*} = 90\,\text {m}$ at low instantaneous luminosity and correspond to an integrated luminosity of $37.5{\,\text {nb}^{-1}}$. The single-diffractive dijet cross section $\sigma ^{{\text{ p }{}{}} {\text{ X }}}_{\mathrm {jj}}$, in the kinematic region $\xi 40\,\text {Ge}\text {V}$, and pseudorapidity $|\eta | < 4.4$, is 21.7 \pm 0.9\,\text {(stat)} \,^{+3.0}_{-3.3}\,\text {(syst)} \pm 0.9\,\text {(lumi)} \,\text {nb} . The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of $\xi$, is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range $-2.9 \le \log _{10} x \le -1.6$, is $R = (\sigma ^{{\text{ p }{}{}} {\text{ X }}}_{\mathrm {jj}}/\Delta \xi )/\sigma _{\mathrm {jj}} = 0.025 \pm 0.001\,\text {(stat)} \pm 0.003\,\text {(syst)}$, where $\sigma ^{{\text{ p }{}{}} {\text{ X }}}_{\mathrm {jj}}$ and $\sigma _{\mathrm {jj}}$ are the single-diffractive and inclusive dijet cross sections, respectively. The results are compared with predictions from models of diffractive and nondiffractive interactions. Monte Carlo predictions based on the HERA diffractive parton distribution functions agree well with the data when corrected for the effect of soft rescattering between the spectator partons

First search for exclusive diphoton production at high mass with tagged protons in proton-proton collisions at s=\sqrt{s} = 13 TeV

International audienceA search for exclusive two-photon production via photon exchange in proton-proton collisions, pp $\to$ p$\gamma\gamma$p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb$^{-1}$ collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeV at the LHC. Events are selected with a diphoton invariant mass above 350 GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons matches the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% CL are $\lvert\zeta_1\rvert$ $\lt$ 2.9 $\times$ 10$^{-13}$ GeV$^{-4}$ and $\lvert\zeta_2\rvert$ $\lt$ 6.0 $\times$ 10$^{-13}$ GeV$^{-4}$