Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266

RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam

The RF system is a part of the 1.6 - 2 MeV injector for the Race-Track Microtron - Recuperator (RTMR) that is under construction at BINP, Novosibirsk, for the Center of Photochemistry. RF system has three 180.4 MHz cavities. Buncher cavity operates at the accelerating voltage of 100 kV and two accelerating cavities operate at the gap voltage up to 800 kV. Cavities are driven by 3 power amplifiers. Maximum output power of amplifier which feeds the accelerating cavity is 130 kW. Low level electronics controls phase and amplitude of RF cavity gap voltages and generates signals for synchronization of the electron gun. Maximum current of injector (45 mA) is realized at 22.5 MHz repetition rate of electron bunches. The effects of beam – RF cavities interaction and the RF system operation results are presented

Measurement of the branching fraction of J/ψ→ρπJ/\psi\rightarrow\rho\pi at KEDR

We present the study of the decay $J/\psi \rightarrow \rho \pi$. The results are based on of 5.2 million $J/\psi$ events collected by the KEDR detector at VEPP-4M collider. The branching fraction is measured to be $\mathcal{B}(J/\psi\rightarrow\rho\pi) = \big(2.072\pm 0.017 \pm 0.056 \big)\cdot 10^{-2}$ where the first uncertainty is statistical, the second one is systematic. This is the most precise single measurement of this quantity at the moment

Design and Construction of the Linac4 Accelerating Structures

The Linac4 project at CERN is at an advanced state of construction. Prototypes and/or operational modules of the different types of accelerating structures (RFQ, buncher, DTL, CCDTL, and PIMS) have been built and are presently tested. This paper gives the status of the cavity production and reviews the RF and mechanical design of the various structure types. Furthermore the production experience and the first test results shall be presented