Tesi etd-10092012-123509 |
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Tipo di tesi
Tesi di laurea specialistica
Autore
LOVECCHIO, COSIMO
URN
etd-10092012-123509
Titolo
A large atoms number magnetic trap for BEC production
Dipartimento
SCIENZE MATEMATICHE, FISICHE E NATURALI
Corso di studi
SCIENZE FISICHE
Relatori
relatore Prof. Mannella, Riccardo
Parole chiave
- BEC
- magnetic trap
Data inizio appello
25/10/2012
Consultabilità
Non consultabile
Data di rilascio
25/10/2052
Riassunto
This thesis describes an experimental apparatus and the operative procedures leading to load a population of 87Rb atoms in a magnetic trap. The machine used is devoted to the high rate production of Bose-Eintein Condensates (BECs).
An integral part of the system is the magneto-optical trap (MOT), where a cloud of atoms can be trapped and cooled by a spatially modulated force from atom-photon momentum exchange. Our experiment is based on a double MOT apparatus where a ve beams MOT acts as a source of slow atoms for a second six beam MOT in the Ultra High Vacuum (UHV) region. The light with the necessary properties to slow the atoms (power stability, spectral purity, spatial homogeneity) is produced with a Master Oscillator Power Amplier (MOPA) laser system. The resulting power for each beam used
for the MOTs exceeds the saturation intensity of the F = 2 -> F' = 3 transitions (saturated MOT). The number of atoms trapped with this set-up is of the order of 10^8.
The magnetic trap setup is a quadrupole and Ioe trap conguration (QUIC trap), which consists of a pairs of coils in anti-Helmoltz conguration and an Ioffe coil. They can produce a magnetic eld gradient up to 500 G/cm and allow easy optical access to the experiment.
Magneto-optically trapped atoms are compressed, cooled by the optical molasses technique, and then optically pumped into the |F_g = 2;m_F = 2> state before being loaded into the quadrupole trap. With a transfer effciency of 52
percent from the second MOT into the magnetic trap, this setup is capable of maintain the trapped atoms for a time of 45+/-4 s.
The atomic cloud released from the magnetic trap is probed by absorption imaging to determine the number of trapped atoms.
The next steps in order to produce a BEC are the changing of the trap conguration to the QUIC trap and the RF evaporative cooling process, to force the condensation of trapped atoms.
An integral part of the system is the magneto-optical trap (MOT), where a cloud of atoms can be trapped and cooled by a spatially modulated force from atom-photon momentum exchange. Our experiment is based on a double MOT apparatus where a ve beams MOT acts as a source of slow atoms for a second six beam MOT in the Ultra High Vacuum (UHV) region. The light with the necessary properties to slow the atoms (power stability, spectral purity, spatial homogeneity) is produced with a Master Oscillator Power Amplier (MOPA) laser system. The resulting power for each beam used
for the MOTs exceeds the saturation intensity of the F = 2 -> F' = 3 transitions (saturated MOT). The number of atoms trapped with this set-up is of the order of 10^8.
The magnetic trap setup is a quadrupole and Ioe trap conguration (QUIC trap), which consists of a pairs of coils in anti-Helmoltz conguration and an Ioffe coil. They can produce a magnetic eld gradient up to 500 G/cm and allow easy optical access to the experiment.
Magneto-optically trapped atoms are compressed, cooled by the optical molasses technique, and then optically pumped into the |F_g = 2;m_F = 2> state before being loaded into the quadrupole trap. With a transfer effciency of 52
percent from the second MOT into the magnetic trap, this setup is capable of maintain the trapped atoms for a time of 45+/-4 s.
The atomic cloud released from the magnetic trap is probed by absorption imaging to determine the number of trapped atoms.
The next steps in order to produce a BEC are the changing of the trap conguration to the QUIC trap and the RF evaporative cooling process, to force the condensation of trapped atoms.
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