Performance of the COMPASS polarized target dilution refrigerator

✍ Scribed by N. Doshita; J. Ball; G. Baum; P. Berglund; F. Gautheron; St. Goertz; K. Gustafsson; T. Hasegawa; N. Horikawa; S. Ishimoto; T. Iwata; Y. Kisselev; J. Koivuniemi; K. Kondo; T. Matsuda; W. Meyer; G. Reicherz; N. Takabayashi

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 259 KB
• Volume: 526
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2004.03.164

✦ Synopsis

The dynamic nuclear polarization (DNP) of 6 LiD requires 1 mW=g or more microwave power in the beginning of the process. With the material of 350 g; this gives more than 350 mW in total for the COMPASS polarized target. A temperature around 300 mK or below is needed for an efficient polarization. These low temperatures can only be achieved with a dilution refrigerator designed to operate with a 3 He flow of 100 mmol=s: In order to keep the polarization in the frozen mode, temperatures of about 65 mK are used with typical magnetic relaxation times of more than 1400 h at 0:42 T and of more than 15 000 h at 2:5 T: Low lattice temperature is important in achieving high nuclear polarization. The base temperature is limited by the heat brought to the mixing chamber by the inlet 3 He and by radiation and conduction of heat.