Peter Schury edited section_Plan_for_use_of__.tex  over 8 years ago

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Unfortunately, the initial commissioning of the system was more difficult and time-consuming than initially supposed. While we have succeeded in the preliminary commissioning, including several actinide atomic mass measurements, doing so required the use of nearly all the initially assigned machine time. However, at the same time, the commissioning proved that we can simultaneously measure several isotopes, providing a new option for efficient use of future machine time. Additionally, the development of projectile beams of Ti and Cr give us the ability to extend our initial area of interest up to isotopes of Sg.  \subsection{Isotopes to be produced with $^{40}$Ar beams}  We still require some machine time with a $^{40}$Ar beam. We will need some time to make an online verification of improvements in recapture in the second trap system using the well-studied $^{205}$Fr and $^{201}$At. We will also need this beam for study of neutron-deficient Fm produced via $^{208}$Pb($^{40}$Ar, $x$n)$^{248-x}$Fm. However, we must increase the efficiency of recapturing ion pulses in the second trap to perform meaningful mass measurements of $^{244, 245}$Fm in a reasonable time. The masses of $^{244, 245}$Fm can be measured simultaneously.  \subsection{Isotopes to be produced with $^{48}$Ca beams}  As in our original proposal, we plan to utilize a $^{48}$Ca beam for production of Md, No and Lr isotopes near $N$=152. The isotopes we wish to study are shown in yellow in Fig.~\ref{figN152Isotopes}. Even with the efficiency seen thus far, for most of these isotopes we can make meaningful mass measurements within 1 week of machine time. This will be discussed in more detail in the following section. Based on our experience in commissioning experiments, we should be able to measure several of these isotopes simultaneously by using multiple types of targets in the target wheel. This will allow for some reduction in the requisite machine time and allow isotopes previously measured via Penning trap to be used as mass references.  \subsection{Isotopes to be produced with $^{50}$Ti beams}  Using the recently available $^{50}$Ti beam, with the demonstrated intensity of 500~pnA, we wish to study $^{256, 257}$Rf and $^{257, 258}$Db, shown in green in Fig.~\ref{figN152Isotopes}. The rates are sufficient, even with our present system efficiency, to make meaningful mass measurements of these four isotopes within 1 week of machine time. This will be discussed in more detail in the following section. By using multiple types of targets in the target wheel, we will be able to measure all four of these isotopes simultaneously. This will somewhat reduce the requisite machine time and allow for increased precision in measurement of the mass differences among these isotopes.  \subsection{Isotopes to be produced with $^{54}$Cr beams}  A primary beam of $^{54}$Cr is currently under development at RILAC. While the available intensity is unknown at this point, if an intensity of 500~pnA were to be available we would be able to perform meaningful mass measurements of $^{260, 261}$Sg (shown in blue in Fig.~\ref{figN152Isotopes}) within 1 week of machine time even with the current system efficiency. This will be discussed in more detail in the following section. These two isotopes, along with any p$x$n evaporation channels, will be able to be measured simultaneously.  \subsection{Isotopes to be produced with $^{14}$N, $^{15}$N, and $^{22}$Ne beams}  Using primary beams of N and Ne with actinide targets, we plan to measure No and Lr isotopes with $N>$153. These isotopes are shown in red and browns in Fig.~\ref{figN152Isotopes}. In order to make meaningful mass measurements in a reasonable time will require an improvement in the efficiency of recapturing ion pulses in the second trap. Among these isotopes, $^{256, 257}$No and $^{258-260}$Lr will each be able to be measured simultaneously.