Upgrading Of Schottky Experimental Platform And Ion Lifetime Measurement At CSRe

Precision mass and half-life measurements of the short-lived nuclei are the research frontiers in modern nuclear physics.In highly-charged ions（HCIs）,compared to the neutral atoms,exotic decay channels may appear,and decay half-life may change for the atomic nuclei.The experimental platform based on Schottky detectors installed at the heavy ion storage rings is one of the excellent tools for studying these phenomena.The radioactive HCIs can be stored in the storage ring for an excessively long time due to ultra-high vacuum（UHV）conditions.The ions’motion can be measured undisturbed by the Schottky detectors.The mass-to-charge ratios,as well as the numbers of the stored ions,can be calibrated in the measured revolution frequency spectra.From the decay curve of the frequency peak area as a function of time,the half-life of the stored ions can be deduced.In order to do diverse nuclear experiments using the Schottky detectors in the ex-perimental Cooler Storage Ring（CSRe）in Lanzhou,functions such as long-time data acquisition（DAQ）and online data analysis are needed.In this thesis,I have upgraded the current Schottky experimental platform at CSRe.A new DAQ system,as well as an online data analysis and monitoring system,have been designed and implemented with user-friendly interfaces.The storage half-lives of the⁸⁶Kr projectile fragments in the CSRe were measured with the newly developed DAQ system.The results revealed many facts about the conditions of the CSRe storage ring,pointing out the improve-ment directions for new Schottky experiments in the future.The main research works are summarised as follows:·Upgrade of the Data Acquisition（DAQ）system for the CSRe Schottky experi-mental platform.Combining an R&S IQR100 data recorder and an R&S FSVR7 spec-trum analyzer enables long-time data acquisition and large-file storage.An indepen-dent trigger system was newly installed for the data recorder to enable triggered DAQ mode.A control program with Graphical User Interface（GUI）was developed aiming at flexible and efficient DAQ functions.Online and offline data analysis tools were also developed,and spectrum analysis and Particle IDentification（PID）algorithms were in-cluded.With the new data acquisition and analyzing system,ion information in the ring can be obtained in real-time,providing online feedback for experimentalists and the CSRe machine operators.This work has laid a solid foundation for the time-resolved Schottky Spectrometer in CSRe.·Development of a new baseline estimation algorithm Br PLS.Starting from the penalized least squares（PLS）method,a unified weight assignment was deduced from the Bayesian theorem,and the baseline of any spectrum can be obtained in an itera-tive algorithm without knowing the analytical baseline form.The algorithm was named Bayesian re-weighted PLS（Br PLS）,and the performance is quite good in achieving reasonable baselines despite of random noise,various baseline shapes,and signal peak locations.Because no pre-identifying of the signal peaks and no knowledge of the base-line shapes are needed,this baseline estimation algorithm is universally applicable in any spectrum analysis task.The Br PLS algorithm was implemented in the online data analysis program to enable automatic baseline correction in the measured Schottky spec-trum.Accurate ion storage lifetime was deduced from the peak area of the baseline corrected spectrum.The Schottky experimental platform developed in this work will play a significant role during the ongoing upgrading of the CSRe electron cooling device.With a work-ing electron cooling capability in CSRe,the available research programs will be greatly expanded at the CSRe Schottky experimental platform.The technology developed in this work will also be used in the next-generation high intensity heavy-ion accelerator HIAF,supporting tasks such as accelerator operation,machine studies,and experimen-tal physics research.