CERN: The ATRAP Experiment

Preview Overview of the ATRAP Experiment  History  Ongoing work  Goals Presentation of my jobs and projects

History Evolved from the TRAP Collaboration  One of the first groups to significantly slow antiprotons

The Experiment  Three phases:  Use antiprotons from the AD to construct antihydrogen  Use drastically slowed antiprotons to make “cold” antihydrogen  Trap and stack the cold antihydrogen

Phase I Antiprotons from the AD are directed into the vertical trap using magnetic fields Positrons from a radioactive source enter the trap from above The two streams of particles combine to form high energy antihydrogen Phase I has been successfully completed

Diagram of Trap

Phase II Slow antiprotons in the trap  Incoming antiprotons ~5-6MeV  Slowed antiprotons cooled to ~4K Add positrons to make “cold” antihydrogen Phase II has been successfully completed

Picture of Trap

Phase III Trap the cold antihydrogen atoms  Using a quadrupole magnet, make a non- uniform magnetic field in the trap  Neutral antihydrogen atoms will drift towards the region where the field is weakest

Phase III (cont.) Use laser spectroscopy to study the trapped antihydrogen Compare the properties of the antihydrogen with hydrogen The ATRAP team is currently working on Phase III

Two Zones All previous experimentation has been done in a single zone Second zone under construction to allow further and more extensive tests

Zone 2 Contains significantly larger superconducting magnet Allows a larger trap that can be used for further experimentation  Trap used in Zone 1 can only contain small clouds of particles  Larger diameter of trap in Zone 2 will allow containment of larger clouds of particles

My Projects Helping maintain current experimental equipment in Zone 1 Assisting ATRAP team members prepare Zone 2 for initial testing

Work in Zone 1 Daily tasks  Kept the magnets and trap at 4K by helping to refill the liquid Helium reservoirs Minor Projects  Monitored stress on magnet during ramp up testing  Heat treated the reflection moderator

Reflection Moderator (R-Mod) Polished 2mm tungsten crystal Multiple applications for antihydrogen production  Facilitate manufacture of Rydberg positronium  Produce cold plasmas of pure positrons

R-Mod Preventive Maintenance Moderator must be purified periodically to ensure proper operation Purification technique involves heat treating the r-mod

Heat Treatment Procedure Moderator is placed in an evacuated oxygen atmosphere (P~1x10 -6 Torr) “Bake off” impurities  Heated by an electron beam to 1200° C for 30 minutes  Held at 2150° C for 5 minutes with oxygen atmosphere reduced (P~1x10 -7 Torr)

Heat Treatment Procedure (cont.) Pressure closely monitored while the moderator is at the higher temperature After a series of repetitions, the pressure increase falls below predefined threshold Moderator slowly brought back to room temperature

Heat Treatment Setup

Work in Zone 2 Help Prepare Zone 2 for initial testing  Installation of safety equipment  Fabricate circuits for measurement devices  Preparation of Faraday Cage

Circuit Fabrication Trap usage requires rapid voltage and power swings Special relay circuits designed to achieve the desired results

Faraday Cage Preparation Making and running shielded cables from the zone to the cage Setting up computer for remote operation of equipment in the zone Installing variety of measuring equipment

Faraday Cage Preparation (cont.)

Conclusion Ultimate goal of ATRAP is to produce, contain, and study cold antihydrogen My ATRAP experience was multifaceted  Tasks in Zone 1 entailed working on an ongoing experiment  Work in Zone 2 involved the preparation and planning before the beginning of an experiment

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