The User-friendly On-line Diffusion Chamber Jaime E. Avilés Acosta

Outline 1)What experiment did I work on? 2)What is the experiment’s goal? 3)What was my project? 4)What was done and what is yet to be done? 5)Future prospects for the On-line Diffusion Chamber

The Experiment On-line Diffusion Chamber (ODC) built in 2009 by team from Universität des Saarlandes The ODC is a stand-alone apparatus for radiotracer diffusion studies Uses a radioactive isotope beam source to implant radioactive impurities in a target material Spectrum Master X-Cooler II

The Experiment So, how does it work…? Spectrum Master X-Cooler II

Annealing Manipulator arm extends target to oven Target annealed to diffuse implanted radioisotopes After annealing, target is drawn back to chamber The Experiment Spectrum Master X-Cooler II Ablation Argon gas is ionized and then accelerated with a 60 kV potential Ion gun ablates target’s surface Ejected material and implanted radioisotopes cling to tape

X-Cooler II Tape transport and diffusion profiling Tape moves over gamma detector that operates at ~80 K Detector records intensity of radiation over time Data are used to build a diffusion profile of the radioisotope in target. The Experiment Spectrum Master

What’s so special about the ODC? Direct access to on-demand production of radionuclides at ISOLDE The experiment is run almost only with a LabView program—all data is stored in the computer running it The Goal The purpose of the ODC is to carry out studies with short-lived radioisotopes or nuclear isomers (half-lives in tens of minutes) However, the ODC was too unwieldy and complicated for visiting researchers to carry out experiments in a short period of time.

The purpose of the experiment is to do studies with very short- lived radioisotopes or nuclear isomers (half-lives in minutes or less) My Project Make the ODC more mobile and easier to plug-in/plug-out of beam line Calibration of peripherals (ion gun, Ge detector, Faraday cup, etc.) Improve execution timing of LabView code of Virtual Instrument that controls ODC peripherals Test apparatus with stable beams and radioactive isotope beams— compare results to offline diffusion apparatus

Software Changes Added annotations throughout the LabView block panel (the “code”) Wrote an in-depth guide to explain how it works Removed unnecessary flat-sequence structures to enable parallel processing Faraday Cup on the ODC couldn’t extend fully due to a series of misused variables and booleans, now replaced

Software Changes Most of the time, the program periodically scans for output from all the peripherals and stores the data Modified the code to add a timing functionality to see if changes in the code improved execution timing Scanning time improved by an average of 71.8 ms (the scan takes ~2 seconds, it runs 24 functions, with 83 ms per function). Numerous other miscellaneous changes—all changes have been logged for future reference

Hardware Changes Assembled a new three-phase plug for the ODC’s controller rack Added two pressure gauges and two needle gauge displays Added a turbo motor pump Added a halogen LED inside the chamber Installed heavy duty wheels (no more forklift needed!) Calibrated Faraday Cup pre-set positions and the target holder’s origin’s position (0 mm) Attached cooling fan to turbo motor pump

Hardware Issues After cooling down, Ge gamma detector didn’t seem operational Tried to bias detector with multiple HV supplies with no luck Warmed and cooled down detector again over a 48 hour period Feedback from Ortec DSPEC Jr signal processor suggested power failure Used a HV supply with an ammeter—current wouldn’t drop despite increasing voltage The above suggests a short-circuit in detector

The Future of the ODC Ge gamma detector will be sent to GSI for further diagnosis and for repairs A draft of a complete user guide for the ODC will be compiled Future students will finish calibrations, tests, and improvements (with the help of new documentation, of course) The much more user-friendly ODC will allow future users to use it for studies with short-lived radioisotopes during their short stays at CERN

Acknowledgement My adviser, Karl Johnston Torben Molholt Haraldur “Palle” Gunnlaugsson João Guilherme The rest of the staff at The University of Michigan Indiana University Bloomington CERN

Questions? Spectrum Master X-Cooler II