Thesis (MSc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: A magneto optical trap (MOT) is capable of trapping a vapor cloud consisting
of atoms cooled down to the micro Kelvin range. Three orthogonal pairs of
counter-propagating laser beams of the correct circular polarisation form an
optical molasses which facilitates the cooling of neutral atoms. Additionally
a spatially non-uniform magnetic field produced by two current carrying coils
in a Maxwell gradient configuration is used to trap the cooled atoms. In this
report the effects of the trap parameters, including the laser beam intensity and
frequency detuning, beam diameter and magnetic field gradient, on the number
of trapped atoms are discussed. Secondly the development of an experimental
setup for laser cooling and trapping of 87Rb atoms in vacuum with the aid of a
MOT is presented. All trap components were implemented and characterised.
The vacuum system and trapping chamber in which the cooling takes place
were designed and constructed. A rubidium getter to act as a source of atoms
was integrated into the vacuum system. The two external cavity diode lasers
used for trapping and optical re-pumping were characterised. The optical setup
required for the optical molasses was designed, constructed and characterised.
Saturated absorption spectroscopy was performed to investigate the hyperfine
structure of 87Rb and to frequency lock the lasers. We report on the current
status of the project with regards to progress, results and future work. / AFRIKAANSE OPSOMMING: 'n Magneto-optiese val (magneto optical trap, MOT) kan 'n dampwolk van
atome vang en afkoel tot in die mikro Kelvin bereik. Drie ortogonale pare
laserbundels, elke paar voortplantend in teenoorgestelde rigtings, met die korrekte
sirkelvormige polarisasie vorm 'n sogenaamde optiese molasse wat die
afkoeling van neutrale atome moontlik maak. Bykomend word 'n ruimtelik
nie-uniforme magneetveld geproduseer deur twee stroomdraende spoele in 'n
Maxwell gradient-opstelling gebruik om die afgekoelde atome te vang. In hierdie
verslag word die invloed van die val parameters, insluitend die laserbundel
intensiteit en frekwensie afstemming, die laserbundel deursnit en magneetveld
gradiënt, op die aantal atome in die val bespreek. Tweedens word die ontwikkeling
van 'n eksperimentele opstelling vir laser afkoeling en vang van 87Rb atome
in vakuum met die hulp van 'n MOT voorgelê. Alle komponente van die val
is geïmplementeer en gekarakteriseer. Die vakuumsisteem en val-kamer waarin
die afkoeling plaasvind is ontwerp en gebou. 'n Rubidium gasbinder is in die
vakuumsisteem ingebou om as 'n bron van atome te dien. Die twee eksterne
resonator diodelasers wat gebruik is vir die val en die optiese terugpomp is
gekarakteriseer. Die optiese opstelling wat nodig is vir die optiese molasse is
ontwerp, gebou en gekarakteriseer. Versadigde absorpsiespektroskopie is uitgevoer
om die hiperfynstruktuur van 87Rb te ondersoek en om die lasers se
frekwensies te stabiliseer. Verslag word gedoen oor die huidige stand van die
projek wat betref vordering, resultate en toekomstige werk.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6492 |
| Date | 03 1900 |
| Creators | Rigby, Charles Ian |
| Contributors | Steenkamp, Christine M., Rohwer, Erich G., University of Stellenbosch. Faculty of Science. Dept. of Physics. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 47 p. : ill. |
| Rights | University of Stellenbosch |
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