The Isochronousn Ass Spectrometry Of ¹¹²Sn And ⁷⁸Kr Fragments In Storage Ring

Nuclear mass is a fundamental quantity of nucleus,playing an important role in nuclear astrophysics and other areas of physics.Isochronous mass spectrometry(IMS)established in heavy-ion storage rings has proven to be a powerful tool for mass measurements of short-lived nuclei.Based on the Heavy Ion Research Facil-ity in Lanzhou(HIRFL),we have conducted a lot of important mass measurement experiments.Considering the important role of neutron deficient nuclei in the astrophysical up and rp process,we have performed three different IMS experiments using 112Sn as the primary beam.This thesis gives a description of these experiments and corresponding data analysis.For the first time,we obtained the experimental mass value of 82Zr and 84Nb with mass uncertainties of about 10 keV.Also the mass precisions of 79Y?81Zr and 83Nb have been improved to about 100 keV.Combining with extrapolated masses of related nuclei,we pointed out the predicted island of low alpha separation energy of Mo may not exist.The proton and alpha separation energies of many nuclei have been updated.This could have an important impact on the Zr-Nb cycle in rp process as well as the vp process.To make corrections for the effect of the non-synchronism and improve the performance of mass measurement,two new time-of-flight(TOF)detectors were installed in one of the straight sections of the experimental cooler storage ring.The Double-TOF system was tested online for the first time in 2013 with 78Kr fragments.In this thesis,we analysed the experiment data and give the performance of the two TOF detectors.For the most important velocity measurement,we found that serious and stochastic non-synchronism can be induced by using two oscilloscopes to record the signals of the two TOF detectors independently.It can influence the accuracy of the measured velocity greatly.So in the following Double-TOF experiment,we utilized only one oscilloscope to collect data to reduce the non-synchronism.Now we are developing new method to correct the non-synchronism and the data analysis is in process.In addition,we have developed the data analysis method in many aspects.For the first time,we studied the ion identification method in detail in the level of single injection,and invented a totally new method to calculate the ions' average orbit and eliminate the influences on ion's revolution time introduced by the instability of magnetic field of CSRe.This method is very useful specifically in online experiment.Starting from the basic formula,we gave an unambiguous approach to describe the effect of unstable magnetic field on revolution time,from which we can see clearly that unstable magnetic field leads not only the shift of revolution time but also stretching or compressing.This expression can provide mathematical basis for the improvement of traditional magnetic correction method.We pointed out that only using the ions whose storage time is longer than 186?s(about 300 circles)can reduce calculation amount greatly but it can also lead the selection of ions according to their atomic number Z and momentum.This may introduce a systematic deviation in the mass calibration procedure.So we removed this restriction by applying the latest GPU parallel program in the data analysis.