Supercritical water convection loop control system

The Convection Loop control system for research of water parameters in supercritical and "nearby" critical state is considered. Results of experiments are presented.Разработана и изготовлена система управления сверхкритической конвекционной водной петлей. Представлены структурная схема и характеристики системы управления. Выбраны режимы управления для проведения экспериментов. Приведены результаты экспериментов со сверхкритической конвекционной водной петлей на ускорителе ЛУ-10.Розроблена і виготовлена система управління надкритичною конвекційною водною петлею. Представлені структурна схема та характеристики системи управління. Обрано режими управління для проведення експериментів. Наведено результати експериментів з надкритичною конвекційною водною петлею на прискорювачі ЛУ-10

Search for light pseudoscalar sgoldstino in K- decays

A search for the light pseudoscalar sgoldstino production in the three body K- decay K-->pipi0P has been performed with the ISTRA+ detector exposed to the 25 GeV negative secondary beam of the U70 proton synchrotron. No signal is seen. An upper limit for the branching ratio Br(K->pipi0P), at 90% confidence level, is found to be around 9*10**-6 in the effective mass m(P) range from 0 till 200 MeV, excluding the region near m(pi0) where it degrades to 3.5*10**-5.Comment: 10 pages, LATEX, 8 EPS figures, revised version, to be published in Phys.Lett.

High statistic measurement of the K- -> pi0 e- nu decay form-factors

The decay K- -> pi0 e- nu is studied using in-flight decays detected with the ISTRA+ spectrometer. About 920K events are collected for the analysis. The lambda+ slope parameter of the decay form-factor f+(t) in the linear approximation (average slope) is measured: lambda+(lin)= 0.02774 +- 0.00047(stat) +- 0.00032(syst). The quadratic contribution to the form-factor was estimated to be lambda'+ = 0.00084 +- 0.00027(stat) +- 0.00031(syst). The linear slope, which has a meaning of df+(t)/dt|_{t=0} for this fit, is lambda+ = 0.02324 +- 0.00152(stat) +- 0.00032(syst). The limits on possible tensor and scalar couplings are derived: f_{T}/f_{+}(0)=-0.012 +- 0.021(stat) +- 0.011$(syst), f_{S}/f_{+}(0)=-0.0037^{+0.0066}_{-0.0056}(stat) +- 0.0041(syst).Comment: 11 pages, 8 figures. Accepted by Phys.Lett.

Measurement of the Dalitz plot slope parameters for K- -> pi0 pi0 pi- decay using ISTRA+ detector

The Dalitz plot slope parameters g, h and k for the K- -> pi0 pi0 pi- decay have been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV negative secondary beam of the U-70 PS. About 252 K events with four-momenta measured for the pi- and four involved photons were used for the analysis. The values obtained g=0.627+/-0.004(stat)+/-0.010(syst), h=0.046+/-0.004(stat)+/-0.012(syst), k=0.001+/-0.001(stat)+/-0.002(syst) are consistent with the world averages dominated by K+ data, but have significantly smaller errors.Comment: LaTeX, 10 pages, 8 eps-figures, update of IHEP 2002-1

Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup

The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been observed. The sign and value of Fv-Fa have been measured for the first time. The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.Comment: Published in Phys. Lett.

High statistic study of the K- -> pi0 mu- nu decay

The decay K- -> pi0 mu- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer. About 540K events were collected for the analysis. The lambda+ and lambda0 slope parameters of the decay form-factors f+(t), f0(t) have been measured : lambda+ = 0.0277+-0.0013 (stat)+-0.0009 (syst), lambda0 = 0.0183+-0.0011(stat)+-0.0006(syst), and d(lambda0)/d(lambda+)=-0.348. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=-0.0007 +- 0.0071, fS/f+(0)=0.0017 +- 0.0014. No visible non-linearity in the form-factors have been observed.Comment: 11 pages, 8 EPS figures, accepted by Physics Letters

Regimes of irradiation by electrons of samples of materials in supercritical water convection loop

The specially designed in the NSC KIPT Supercritical Water Convection Loop (SCWCL) with an irradiation chamber coupled to an electron accelerator LPE-10 gives an opportunity for corrosion and mechanical tests of materials under electron irradiation. Specimens in water flow are irradiated by the 10 MeV/10 kW electron beam of the LPE-10 linear accelerator at 23…25 MPa and 350…400°C. Presented are the irradiation regime parameters for the 500 hours long work session of the SCWCL.Спеціально розроблена в ХФТІ надкритична водяна конвекційна петля (НВКП) з камерою опромінення, яка зв’язана з прискорювачем електронів ЛПЕ-10, дозволяє проводити корозійні тести потенційних конструкційних матеріалів реакторів IV покоління з надкритичним водяним охолодженням (SCWR) під опроміненням. Зразки в потоці води при 350…400°C, 23…25 МПа опромінюються 10 МеВ/10 кВт електронним пучком лінійного прискорювача ЛПЕ-10. Приводяться параметри режимів опромінення зразків під час 500-годинного сеансу роботи НВКП.Специально разработанная в ХФТИ сверхкритическая водяная конвекционная петля (СВКП) с камерой облучения, связанная с ускорителем электронов ЛУЭ-10, позволяет проводить коррозийные тесты потенциальных конструктивных материалов реакторов IV поколения со сверхкритическим водяным охлаждением (SCWR) под облучением. Образцы в потоке воды при 350…400°C, 23…25 МПа облучаются электронным пучком 10 МэВ/10 кВт линейного ускорителя ЛУЭ-10. Приводятся параметры режимов облучения образцов во время 500-часового сеанса работы СВКП

High statistics study of the K- -> pi0 e- nu decay

The decay K- -> pi0 e- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer working at the 25 GeV negative secondary beam of the U-70 PS. About 550K events were used for the analysis. The lambda+ parameter of the vector form-factor has been measured: lambda+ = 0.0286 +- 0.0008 (stat) +- 0.0006(syst). The limits on the possible tensor and scalar couplings have been obtained: f(T)/f+(0)=0.021 +0.064 -0.075 (stat) +- 0.026(syst) ; f(S)/f+(0)=0.002 +0.020 -0.022 (stat) +- 0.003(syst)Comment: LaTeX-2e, epsfig.sty, 10 pages, 7 figures in EPS forma

Vus and lepton universality from kaon decays with the KLOE detector

KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It has also measured the Kl and the K+- lifetime and determined the shape of the form factors involved in kaon semileptonic decays. We present in the following a description of the above measurements and a well organized compendium of all of our data, with particular attention to correlations. These data provide the basis for the determination of the CKM parameter Vus and a test of the unitarity of the quark flavor mixing matrix. We also test lepton universality and place bounds on new physics using measurements of Vus from Kl2 and Kl3 decays.Comment: 23 pages, 12 figures. Submitted to JHE