E. V. Chernysheva

MASHA separator on the heavy ion beam for determining masses and nuclear physical properties of isotopes of heavy and superheavy elements

The MASHA mass spectrometer designed for identifying superheavy elements by their masses is described. The separation efficiency has been measured in the autonomous mode using four calibrated leakages of noble gases. The total separation efficiency of the mass spectrometer with a hot catcher and an ion source based on the electron cyclotron resonance has been determined using the 40Ar beam. Test experiments have been carried out, in which α-active Hg isotopes produced in complete fusion reaction 40Ar + 144Sm → 184 − xnHg + xn, have been detected in the focal plane of the mass spectrometer. The separation time and efficiency have been determined for short-lived Hg isotopes.

A new beam diagnostic system for the MASHA setup

A new beam diagnostic system based on the PXI standard was developed, tested, and used in the MASHA setup experiment. The beam energy and beam current measurements were carried out using several methods. The online time-of-flight energy measurements were carried out using three pick-up detectors. We used two electronic systems to measure the time between the pick-ups. The first system was based on fast Agilent digitizers (2-channel, 4-GHz sampling rate), and the second one was based on a constant fraction discriminator (CFD) connected to a time-to-digital converter (TDC, 5-ps resolution). A new graphical interface to monitor the electronic devices and to perform the online calculations of energy was developed using MFC C++. The second system based on microchannel plate (time-of-flight) and silicon detectors for the determination of beam energy and the type of accelerated particles was also used. The beam current measurements were carried out with two different sensors. The first sensor is a rotating Faraday cup placed in front of the target, and the second one is an emission detector installed at the rear of the target. This system is now used in experiments for the synthesis of superheavy elements at the U400M cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR).

Data acquisition system for the socal plane detector of the mass separator MASHA

The results of the development and the general information about the data acquisition system which was recently created at the MASHA setup (Flerov laboratory of nuclear reactions at Joint institute for nuclear research) are presented. The main difference from the previous system is that we use a new modern platform, National Instruments PXI with XIA multichannel high-speed digitizers (250 MHz 12 bit 16 channels). At this moment system has 448 spectrometric channels. The software and its features for the data acquisition and analysis are also described. The new DAQ system expands precision measuring capabilities of alpha decays and spontaneous fission at the focal plane position-sensitive silicon strip detector which, in turn, increases the capabilities of the setup in such a field as low-yield registration of elements.

MASS-SPECTROMETRIC METHOD TO STUDY THE PROPERTIES OF HEAVY NUCLEI

There is considered a further development of the mass spectrometer MASHA to adapt the gas catcher technique to the mass spectrometric analysis. The ion-optical parameters of the new installation are calculated. These parameters were derived from the simulation of the compound nucleus fusion reaction 48 Ca+ 238 U→ 286 112 * → 283 112+3n. The applicability of this technique for production and investigation of both the SHE nuclei and the heavy neutron-rich nuclei created in the multinucleon transfer (MNT) collisions between 48 Ca, 86 Kr, and 136 Xe as projectiles and 208 Pb as a target is substantiated.