Development of a Liquid Scintillator and of Data ... - Borexino - Infn

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6 Test of a PXE based scintillator for Borexino volumetric exchange with water from the Inner Vessel. To avoid overpressure of the Inner Vessel, a few 100 l water were pumped out of the Inner Vessel prior to the filling. During the filling the pump was working in a mode, that it pumped water out of the Inner Vessel into the buffer tank, and the scintillator was pushed in a passive mode out of the buffer tank into the Inner Vessel. Once the filling was completed, the Inner Vessel was isolated, and the water was drained from the buffer tank. Then the tank was dried with nitrogen and was then ready to be filled again with the next batch of scintillator. The filling of the total volume of PXE (4 tons) was realized in three batches (1 ton, 2 tons, 1 ton). The data taking with the CTF2 can be divided into 5 different phases: 1. Water Run: The data acquisition was first running from March 19 to March 31 (run 706 - 716). At that time, the Inner Vessel was filled with water. These runs were used to calibrate the electronics; and, by measuring the Cerenkov light from muons crossing the detector, to develop criteria to reject these Cerenkov events. 2. 1 Ton Runs: The first ton of PXE was filled in the CTF on June 3rd 2000. The Inner Vessel used in the CTF2 had several small leaks bearing the risk of enlarging under stress. Therefore we filled only 1 ton of PXE in the beginning in order to keep the buoyancy small. Data was taken from June 4th to June 9th (run 717 - 723). After it turned out that there were no substantial leaks, we continued the filling. 3. 3 Ton Runs: Another Ñ were inserted in the IV on June 11th 2000. Data was taken from June 13th until July 15th (run 724 - 757). 4. 4 Ton Runs: The remaining amount of PXE was inserted on July 15th 2000. The data taking period with 4 tons of PXE, without any scintillator operations, lasted from 16th July 2000 until 6th September 2000, i.e. about 6 weeks in total (run 758 - 789). 5. Source Test: From September 12 until September 20 we carried out a number of calibration measurements with a localized source introduced into the Inner Vessel (run 790 -810). The source was placed at various locations inside the Inner Vessel to test the homogeneity of the detector response and the systematic effects of the position reconstruction. The results of these tests will be reported in chapter 7. At the end of September 2000, the scintillator was unloaded from the Inner Vessel into one EP tank by volumetric exchange with water. Later, the PXE was removed from the Module-0 and placed into storage for later use in another experiment. The water was drained from the CTF tank so that the leaky Inner Vessel could be replaced. 86
6.3.4 Results concerning the Radiopurity C Concentration 6.3 The PXE Tests in the CTF In the energy region below 150 keV, the counting rate is dominated by C. The C concentration in the scintillator can be determined by fitting a convolution of the theoretical beta spectrum and the energy dependent detector response plus a background contribution to the measured spectrum (see fig. 6.5). From this fit, the following C concentration was derived [Res01]: ¦ Figure 6.5: PXE data collected in a period of 153 hours with a fit of the C spectrum. Taken from [Res01]. 87
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Fakultät für Physik der Technisch
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Abstract The first chapter contains
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Übersicht an Radionukliden in BORE
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Contents 3 The Counting Test Facili
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Contents viii
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1 Solar Neutrinos Figure 1.1: The p
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1 Solar Neutrinos 1.2 Detection of
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1 Solar Neutrinos With this detecti
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1 Solar Neutrinos 1.2.3 Future Expe
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1 Solar Neutrinos 1.3.2 Astrophysic
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1 Solar Neutrinos Using the unitari
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1 Solar Neutrinos km in the earth.
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1 Solar Neutrinos 16 Solution ¡Ñ
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2 The Borexino Experiment The relat
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2 The Borexino Experiment Figure 2.
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2 The Borexino Experiment 2.2 The D
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2 The Borexino Experiment 2.3 Detec
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2 The Borexino Experiment 2.3.2 Anc
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2 The Borexino Experiment which per
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2 The Borexino Experiment 2.4 Backg
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2 The Borexino Experiment ns; Rn-
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2 The Borexino Experiment volume wo
Page 46 and 47: 3 The Counting Test Facility (CTF)
Page 56 and 57: 4 Position Reconstruction of Scinti
Page 72 and 73: 5 Particle Identification with a Ne
Page 86 and 87: 6 Test of a PXE based scintillator
Page 108 and 109: 7 The Source Runs in CTF2 transpare
Page 110 and 111: 7 The Source Runs in CTF2 7.3 The S
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Page 122 and 123: 7 The Source Runs in CTF2 112 reemi
Page 124 and 125: Summary and Outlook possible to dis
Page 126 and 127: Bibliography [Ade98] E. G. Adelberg
Page 128 and 129: Bibliography [Bra00] L. De Braeckel
Page 130 and 131: Bibliography [Lom97] P. Lombardi, D
Page 132 and 133: Bibliography [Vog96] R. B. Vogelaar
Page 134 and 135: Danksagung An dieser Stelle möchte
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Development of a Liquid Scintillator and of Data ... - Borexino - Infn

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