Pellet Target for PANDA (current status) M. Buescher, A. Boukharov, V. Chernetsky, P. Fedorets, A. Gerasimov, A. Semenov Pavel Fedorets

Current status N2, ø = 17 µm H2, ø = 12 µm Ar, ø = 17 µm 1) Confirmed possibility of mono-disperse and satellite-free droplet production in the triple point chamber for cryogenic liquids: H2, N2, Ar 2) Concentrate on development of various auxiliary systems for long and stable target operation. 3) Tests for definition of the limits of parameters for these systems Pavel Fedorets

Main activities during 2008 1) Improvement of target operation time by decreasing residual impurities. 2) Stabilisation of the thermodynamic parameters in the cryostat. 3) Commissioning of the He filling system. 4) Development and investigation of new stable regimes of the droplet production. Pavel Fedorets

Effect from residual impurities PANDA requirements -> small pellets -> small nozzle -> blocking of the nozzle by frozen crystals of the residual impurities. Hydrogen 7.0 Pavel Fedorets

Effect from residual impurities Pressure (mbar) Time of heating (hour) Measured pressure above the nozzle as function of heating time. Hydrogen 7.0 had been used. Heating start after 4 hours of work. Type of impurity had been identified with mass-spectrometer. Pavel Fedorets

New Purifier New Hydrogen Palladium Purifier HP-50-VCR had been purchased. Achievable purity level for hydrogen is 9.0. All previous tests were with hydrogen 7.0. Pavel Fedorets

Studies for stabilization of thermal-physics parameters For stable operation: stability of the temperature in the condenser -> stability of the temperature of evaporated He -> constant level of liquid He in the bath -> development of He filling system (dedicated He valve) Pavel Fedorets

Commissioning of He filling system First step of commissioning -> modification of He filling system is needed. Drawings for modification had been prepared. Final correction and check before start the production is going on. Pavel Fedorets

Development new regimes of droplet production New generator with maximum f=120 kHz had been constructed and installed Stable mono-disperse droplet production had been observed at f~90-100 kHz for hydrogen and nitrogen hydrogen Ø(nozzle) ≈ 12μm V (droplet) ≈ 10 m/s f ≈ 90 kHz Pavel Fedorets

Main activities in 2009 1) Improvement of target operation time by decreasing residual impurities. Commissioning of palladium purifier. 2) Stabilisation of the thermodynamic parameters in the cryostat. Commissioning of the He filling system. 4) Development and investigation of stable regimes of the pellet production. Continue to development of diagnostic system. Pavel Fedorets

Main activities in 2009, diagnostic system New line scan camera AVIIVA UM2 had been ordered for measurements of pellet flow parameters in scattering chamber and creation of time of flight system in synchronization with CCD cameras observing the triple point chamber. Pavel Fedorets