The heavy ion facility for technological applications is developed at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. The booster synchrotron with electron ...cooling is one of the main parts of the facility. This work presents the beam dynamics simulation with betatron coupling and nonlinearities of the guided magnetic field. The transverse betatron coupling excited by electron cooling solenoid was compensated by the pair of skew quadrupole triplets with antisymmetric supply and located symmetrically relative to the solenoid center. The calculation of the vertical dispersion excited by the magnetic field of toroidal sections of the electron cooler was performed. The accelerator lattice was optimized for minimization of vertical dispersion. Another important factor of the beam dynamics is the tune dependence versus momentum deviation called chromaticity. To correct chromaticity, sextupole magnets are applied. On the other hand, sextupoles excite nonlinear resonances that can lead to significant limitation of the dynamic aperture. The dynamic aperture of the synchrotron was simulated by scanning of horizontal and vertical tunes in conditions of chromaticity and betatron coupling suppression. This method makes it possible to identify dangerous resonances. According to the calculations presented, a scheme with application of six sextupole families are developed. This scheme makes it possible to significantly reduce the influence of most dangerous resonances. The wide area of tunes with a fairly large dynamic aperture for particles with required momentum spread was found in simulations. Selection of the operating point in this particular area makes it possible to reduce the space charge effect on the dynamic aperture. At the chosen operating point, the influence of eddy currents and magnetic fields nonlinearities on the dynamic aperture was investigated.
ABSTRACT
Polarization offers a unique view in the physical processes of astrophysical jets. We report on optical circular polarization (CP) observations of two famous blazars, namely 3C 279 and ...PKS 1510−089, at high linearly polarized states. This is the first time PKS 1510−089 is observed in optical CP. While only upper limits can be extracted from our observing campaign, the non-detection of optical CP allows us to provide meaningful constraints on their magnetic field strength and jet composition. We find that high-energy emission models requiring high magnetic field strength and a low positron fraction can be excluded.
PANDA Phase One Liu, Z.; Liu, B.; Shen, X. ...
The European physical journal. A, Hadrons and nuclei,
06/2021, Letnik:
57, Številka:
6
Journal Article
Recenzirano
Odprti dostop
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future ...antiProton ANnihilations at DArmstadt (PANDA or
P
¯
ANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton–nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model,
e.g.
through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the
Phase One
setup. The physics programme that is achievable during Phase One is outlined in this paper.
Slow resonant extraction from the synchrotron makes it possible to provide relatively stable beams for a long time. The principle of slow extraction is intentionally exciting the third-order ...resonance by controlling detuning and sextupole strength with the gradual release of particles from inside to outside a stable separatrix. The Budker Institute of Nuclear Physics (BINP) develops the ion synchrotron for a wide range of technological applications. This paper describes slow resonant extraction from an ion synchrotron with betatron oscillation excitation by a transverse RF field.
The issue of high-current electron-beam transport in the LIA-5 accelerator is discussed. The results of numerical simulation of beam transport in the 15-m-long LIA-5 accelerator channel are ...presented. The ASTRA macroparticle (PIC) code and two codes developed at the Budker Institute of Nuclear Physics (a code based on the solution of the Kapchinsky–Vladimirsky system of equations (K–V envelope code) and the UltraSAM code implementing the method of boundary integral equations) are used in this simulation. The experimental data agree closely with the simulation results. The electron-beam envelope is reconstructed based on the experimental luminophore data using the K–V envelope code with a genetic algorithm.
We present time-resolved broadband observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. ...While investigating the previously reported gamma -ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears to be delayed with respect to the gamma -ray emission by about 10 days. X-ray observations reveal a pair of "isolated" flares separated by ~90 days, with only weak gamma -ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma -ray flare, while the peak appears in the millimeter (mm)/submillimeter (sub-mm) band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broadband spectra during the gamma -ray flaring event by a shift of its location from ~1 pc to ~4 pc from the central black hole. On the other hand, if the gamma -ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.
Research and development of a safety system for the SPIRAL2 facility has been conceived to protect the UCx target from a possible interaction with the 200kW deuteron beam. The system called “delay ...window” (DW) is designed as an integral part of the neutron converter module and is located in between the neutron converter and the fission target. The device has been designed as a barrier, located directly behind the neutron converter on the axis of the deuteron beam, with the purpose of “delaying” the eventual interaction of the deuteron beam with the UCx target in case of a failure of the neutron converter. The “delay” must be long enough to allow the interlock to react and safely stop the beam operation, before the beam will reach the UCx target. The working concept of the DW is based on the principle of the electrical fuse. Electrically insulated wires placed on the surface of a Tantalum disk assure a so called “free contact”, normally closed to an electronic circuit located on the HV platform, far from the radioactive environment. The melting temperature of the wires is much less than Tantalum. Once the beam is impinging on the disk, one or more wires are melted and the “free contact” is open. A solid state relay is changing its state and a signal is sent to the interlock device. A prototype of the DW has been constructed and tested with an electron beam of power density equivalent to the SPIRAL2 beam. The measured “delay” is 682.5ms (σ=116ms), that is rather long in comparison to the intrinsic delays introduced by the detectors itself (2ms) and by the associated electronic devices (120ns). The experimental results confirm that, in the case of a failure of the neutron converter, the DW as conceived is enable to withstand the beam power for a period of time sufficiently long to safely shut down the SPIRAL2 accelerator.
Project of submillimeter free electron laser (FEL) is developed at BINP in collaboration with IAP 1 . The FEL scheme is based on a high current electron beam (E e = 5−20 MeV, I b = 1−2 kA, τ= 160−200 ...ns) generated at the new linear induction accelerator (LIA) 2 , 3 . According to our theoretical analysis, such beam allows us to generate coherent pulses of submm-radiation in the frequency range 0.3-1 THz. The radiation power in such scheme can reach a sub-megawatt level and the energy content up to ~100 J.
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