Beamtime September 2009
Moderated positrons came through the beamline for the first time

2009-09-15_01 Krasimir Kosev is testing the timing equipment prior to beam time 2009-09-15_02 Additional steering coils can compensate the bending of the 32 MeV beam in the field of the large transport coil (about 1.5 mm) 2009-09-15_03 The big additional coil elongates the transport field through the converter - finally it was not necessary. We switched it off. 2009-09-15_04 The cave 111b setup screened with lead ... 2009-09-15_05 The cooling unit for the big additional coil was screened from radiation by heavy concrete. 2009-09-15_06 ... screening also with PE stones. 2009-09-15_07 PE stones for neutron screening... 2009-09-15_08 After a few minutes having the electron beam still during electron steering, we got the positrons through. Background was 2009-09-15_09 First Doppler line of slow positrons. 2009-09-15_10 Champagne for the first moderated positrons.... 2009-09-15_11 ... in the Lab 111d. 2009-09-15_12 The apperture of 20mm in the beam line. 2009-09-15_13 It is about 80 cm before the target. 2009-09-15_14 Positron beam on MCP. Positrons look green at FZD. 2009-09-15_15 MCP in the vacuum chamber as seen by the video camera. 2009-09-15_16 Video camera at position looking to MCP. 2009-09-15_17 MCP in open beam tube. 2009-09-15_18 Maik is mounting the first sample into the MePS system... 2009-09-15_19 ... it is nanoporous glass, having a long PS component in the spectrum. 2009-09-15_20 This is the time structure of unchopped, unbunched original positron beam at position 6.8m from moderator. 50% of positrons are in a 3ns window. Uncorrelated background was only 3 % in whole area. 2009-09-15_21 First positron lifetime spectrum of nanoporous glass. Repetition time was reduced to 616 ns because of the long positron lifetime. The unbunched/unchopped beam of 2 keV transport energy directly after moderation has been used.

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