Cargando…

Performance of the COMPASS polarized target dilution refrigerator

The dynamic nuclear polarization (DNP) of **6LiD 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. T...

Descripción completa

Detalles Bibliográficos
Autores principales: Doshita, N, Ball, J, Baum, G, Berglund, P, Gautheron, F, Görtz, S, Gustafsson, K K, Hasegawa, T, Horikawa, N, Ishimoto, S, Iwata, T, Kisselev, Yu V, Koivuniemi, J H, Kondo, K, Matsuda, T, Meyer, W, Reicherz, G, Takabayashi, N
Lenguaje:eng
Publicado: 2004
Materias:
Acceso en línea:https://dx.doi.org/10.1016/j.nima.2004.03.164
http://cds.cern.ch/record/816644
Descripción
Sumario:The dynamic nuclear polarization (DNP) of **6LiD 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 **3He 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 15000 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 **3He and by radiation and conduction of heat.