RIA Hands-on Activities

ISOL Radioactive Ion Beam Production using Tandem Beams (Stracener/Batchelder) (2 groups each day)

This activity will involve measurement of radioactive ion beam intensities from a uranium carbide (UC) target coupled to a plasma ion source to demonstrate the ISOL technique of producing radioactive beams. A 40 MeV proton beam will be used to irradiate the UC target where radioactive nuclei are produced via fission. The radioactive atoms are transported to the ion source and a beam of radioactive ions is extracted. A dipole magnet is used to select a beam with a single mass. This beam is collected on a moving tape system and transported to a counting station where a high-purity germanium detector is used to measure the gamma-rays emitted from the decay of the beam particles. The student will operate the isotope separator by tuning for a given mass, setting appropriate collection and counting times, and analyzing the data. Some groups will measure the yields of radioactive nuclei in molecular ion beams to demonstrate techniques that are used to enhance the beam purity. Data collection and analysis will be supplemented with discussions of ion sources and ISOL targets. Each student will be given the opportunity to measure the beam intensity at a given mass and target temperature. The results will be compiled at the end of the week to show yields and beam composition as a function of target temperature.

 

Ion Source Beam Emittance (Liu)

Beam emittance is a crucial property which describes the angular and longitudinal spread of ion beams. The student will learn about the various factors which degrade beam emittance and will measure the emittance from an ion source.

 

Laser Photodissociation of Ions in Mixed-species Beams to Produce Enhanced Purity Beams (Beene/Havener)

The student will produce a beam of negative ions consisting of O and F. The beam will be passed through a gas-filled quadrupole to "cool" the beam and prepare it so that a colinear laser beam can be tuned to a frequency which will remove an electron from the oxygen ions resulting in a beam of "pure" F ions.

 

Microchannel plates and Time-of-flight techniques (Liang/Varner)

A small time-of-flight experiment will be performed with two of the timing detectors used for low intensity beam tracking and timing. The students will learn how to use these detectors to track real particles in presence of noise. The experimenters will take data using an unknown alpha emitter and use the TOF data to identify the alpha source and maybe estimate its intensity.

 

Measurements with the HRIBF windowless gas target (Blackmon/Smith/Bardayan)

The HRIBF windowless gas target allows nuclear reaction studies in inverse kinematics with gaseous elements such as hydrogen and helium. The target is of particular interest for nuclear astrophysics studies and has been used to measure proton capture and (p,α) reactions. The target consists of series of differential pumping stages that achieves a pressure drop of a factor of several million over a length of about half a meter. Students will learn to operate the HRIBF windowless gas target and will perform measurements using an alpha source to determine the areal density of the target and to measure the stopping power for alpha particles in nitrogen gas.

 

Digital Signal Processing (Rykaczewski/Grzywacz) (may be able to take 2 groups each day)

Data acquistion based on digital signal processing will be discussed in terms of nuclear structure measurements. The student will characterize and analyze preamp signals from various detectors. The superior functionality of these systems and a comparison with traditional analog electronics will be discussed.

 

Digital Signal Processing 2 (Radford/Yu)

Digital waveform data from a HPGe detector, acquired from a fast digitizer such as used in the activity Digital Signal Processing 1, will be analysed offline. The concepts of pole-zero correction and energy filters will be discussed. Students will program digital filters and constant-fraction discriminators to determine both the energy and time of the signals.

 

Theory (Nazarewicz/Dobaczewski) (can take 2 groups each day)

This will be an informal discussion (involving pen, paper, and whiteboard), in a friendly and relaxed atmosphere, on selected theoretical questions of nuclear structure. Several timely topics have been proposed by the instructors, however, student's suggestions are most welcome! Send an email to Witek Nazarewicz with your suggestions.

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