Multichannel vector field control module for LLRF control of superconducting cavities

The field control of multiple superconducting RF cavities with a single Klystron, such as the proposed RF scheme for the ILC, requires high density (number of RF channels) signal processing hardware so that vector control may be implemented with minimum group delay. The MFC (Multichannel Field Control) module is a 33-channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs. A 32-bit, 400MHz floating point DSP provides additional computational and control capability for calibration and implementation of more complex control algorithms. Multiple high speed serial transceivers on the front panel and the backplane bus allow a flexible architecture for inter-module real time data exchanges. An interface CPLD supports the VXI bus protocol for communication to a Slot0 CPU, with Ethernet connections for remote in system programming of the FPGA and DSP as well as data acquisition

Density of states measurements for the heavy subband of holes in HgTe quantum wells

A valence band in narrow HgTe quantum wells contains well-conductive Dirac-like light holes at the Γ point and a poorly conductive heavy hole subband located in the local valleys. Here we propose and employ two methods to measure the density of states for these heavy holes. The first method uses a gate-recharging technique to measure thermodynamical entropy per particle. As the Fermi level is tuned with gate voltage from a light to heavy subband, the entropy increases dramatically, and the value of this increase gives an estimate for the density of states. The second method determines the density of states for heavy holes indirectly from the gate voltage dependence of the period of the Shubnikov-de Haas oscillations for light holes. The results obtained by both methods are in reasonable agreement with each other. Our approaches can be applied to measure large effective carrier masses in other two-dimensional gated systems. © 2020 American Physical Society.The authors are thankful to S. S. Krishtopenko, and I. S. Burmistrov for discussions. The measurements facilities of the LPI were used for entropy detection of the heavy carriers. These measurements were supported by Russian Science Foundation Grant No 18-72-10073. The work has been supported in part by the Russian Foundation for Basic Research (Grant No. 18-02-00050 and 18-29-20053)

Electron cooling of 8-GeV antiprotons at Fermilab's Recycler: Results and operational implications

Electron cooling of 8 GeV antiprotons at Fermilab's Recycler storage ring is now routinely used in the collider operation. It requires a 0.1-0.5 A, 4.3 MeV dc electron beam and is designed to increase the longitudinal phase-space density of the circulating antiproton beam. This paper briefly describes the characteristics of the electron beam that were achieved to successfully cool antiprotons. Then, results from various cooling force measurements along with comparison to a nonmagnetized model are presented. Finally, operational aspects of the implementation of electron cooling at the Recycler are discussed, such as adjustments to the cooling rate and the influence of the electron beam on the antiproton beam lifetime

ДОСВІД ФРАНЦІЇ У СТВОРЕННІ СИСТЕМИ АНТИТЕРОРИСТИЧНОЇ БЕЗПЕКИ НАСЕЛЕННЯ: УРОКИ ДЛЯ УКРАЇНИ

The present is increasingly showing the emergence of crisis situations. The merger of the European and Arab worlds can not take place without armed clashes - there is plenty of evidence in recent armed conflicts and terrorist acts. Unfortunately, Ukraine is not an exception to this acute problem issue. Irreversible globalization brings our state closer to the European Union. At the same time, the Russian Federation is not ready to accept Ukraine's European integration, as a result - armed aggression in the Donetsk and Luhansk Oblasts and the implementation of the anti-terrorist operation and the operation of the united forces.The purpose of the paper is to carry out an analysis of the construction of the antiterrorist response system of France, the study of the National Antiterrorist Response Plan of France, and the justification on this basis of proposals for positive experience for Ukraine.The starting point for the creation of an effective system of counterterrorist response in France was the terrorist attacks of 2015, which showed the weaknesses of the anti-terrorist system and the actual failure of the anti-terrorist units to respond effectively to several terrorist attacks simultaneously, including jointly conducting counter-terrorism measures. Therefore, there was a need to increase the effectiveness of counter-terrorism response throughout the state. Based on the foregoing, France's experience in responding to terrorist threats is unique and requires further study.The experience of establishing a National Antiterrorist Response Plan for France is very useful for Ukraine. Particular attention is required to consider the first part of the anti-terrorist plan, which defines the integration of anti-terrorist units in the national system.It is important that the police and gendarmerie patrols who regularly carry out public order duties on the territory of France take immediate steps to stop the terrorist act and minimize civilian casualties at the third level of counter-terrorism response. This experience is very appropriate for the forces of law enforcement in Ukraine, and therefore it is expedient to carry out additional training in the system of training for the response of the units of the patrol police and the National Guard of Ukraine to terrorist threats, as well as equipping them with new samples of weapons, equipment, means of communication Armored vehicles.It is considered appropriate for the representatives of the National Gendarmerie of France to provide counterterrorist preparations for the second and first level of counter-terrorism response to certain special-purpose detachments of the National Guard of Ukraine in the following areas: conducting special operations on the release of hostages in buildings and various types of transport; planning and conducting of antiterrorist measures, etc.No less important is the second part of the Antiterrorist Plan, which is devoted to the interaction of counter-terrorism response units and optimization of their capabilities. The course of the antiterrorist operation in certain districts of Donetsk and Luhansk oblasts (namely, the execution of military and combat tasks through special operations and counter-dive struggles) also revealed similar issues of organization of interagency cooperation. Therefore, it is appropriate to refine, on the basis of studying the experience of France, the mechanism of interagency cooperation between the special units of the Security Service of Ukraine, the National Police of Ukraine, the National Guard of Ukraine, the State Border Guard Service of Ukraine and the military service of law and order in the Armed Forces of Ukraine. In this case, it is necessary to introduce the experience of the prefect of the department (a representative of local government) in the management of a special operation on the organization of interagency cooperation.Directions of further research will be directed on perfection of the existing system of antiterrorist security of the population of Ukraine.Проведено аналіз побудови системи антитерористичної безпеки населення Франції. Вивчено структуру та зміст Національного плану антитерористичного реагування Франції. Обґрунтовано пропозиції щодо запровадження позитивного досвіду для України