1. CTF at Gran Sasso (overview of the hardware) Richard Ford (SNOLAB) (who has not been in the collaboration since 2004) March 19 th 2010

2. The Underground Halls of the Gran Sasso Laboratory Halls in tunnel off A24 autostrada with horizontal drive-in access Under 1400 m rock shielding (~3800 mwe) Muon flux reduced by factor of ~10 6 to ~1 muon/m 2 /hr BX in Hall C ~20mx20mx100m To Rome ~ 100 km

3. The Borexino Detector

4. CTF tank 900m 3 Borexino water tank

5. Original CTF-1  950 m 3 carbon steel tank with “Permatex” radon barrier lining.  4-ton unsegmented liquid scintillator in Nylon balloon vessel.  100 PMTs with focusing reflectors.  Filled with psuedocumine (PC) and 1.5 g/L PPO.  Veto using floor mounted PMTs.  N2 cover gas on tank.  Showed feasibility of Borexino project [Phys. Let. B422 (1998); AstroP.Phys. 8 (1998)].

6. CTF-1

7. Goals and use of the CTF To demonstrate the unprecedented radio-purity levels that would be needed for Borexino (Th, U ≤ 10 -16 g/g eq. 14 C/ 12 C ≈10 -18 ). To test the various purification techniques and proto-type purification systems (distillation, water-extraction, N2 stripping, and column chromotography). The test the PMT front end electronics, and initial versions of the DAQ and event builders. To test optical transparency and effects such as alpha quenching, and analysis tools such as alpha/beta discrimination techniques. To develop and test ideas for calibration sources. To learn about construction materials and methods (eg. ropes, and nylon vessels). To evaluate alternate scintillator material PXE (CTF-2). To test and commission the full-scale purification plants. Serve as quality control instrument to check sample from each batch of PC delivered (chiefly the 14 C/ 12 C ratio). To do some real physics measurements! (Limits on electron decay and nucleon decay, neutrino magnetic moment, heavy neutrino mixing, Pauli exclusion violation, cosmogenic 11 C production, electron antineutrino interactions, etc – check web site for refs).

8. The Counting Test Facility (CTF3) 4 tonnes of scintillator (PC + 1.5 g/L PPO) 1m radius 500μm Nylon vessel for scintillator 2 m radius “shroud” vessel to shield Rn 3.6 p.e./PMT for 1 MeV electron Muon veto PMTs on floor 100 PMTs (Optical coverage: 21%) Buffer of water – 2.3m vessel to PMT Energy saturation: 6 MeV

9. CTF-1 Process Overview

10. CTF Water Purification System

11. Sample Prompt Event Spectrum in CTF 204 days live-time data:  Raw events 4-tonne mass  Radial cut 70cm  Radial cut 60cm 1 MeV -Background free above 3 MeV, and low backgound above 1MeV -Main source of background is Rn in the buffer water

12. Rn Monitoring System for CTF Sample of gas from the CTF N 2 blanket is dehumidified and pumped to electrostatic chamber. The electrostatic chamber has volume 0.42m 3 and operates at voltage 30kV with a PIN diode detector. Sensitivity achieved is 0.5 mBq/m 3. CTF cover gas activity is typically at about 15 mBq/m 3. Hall C Rn activity is about 100 Bq/m 3 ). The detector is valuable for also monitoring the air inside the CTF tank during installation phases. Note that the large 210 Po peak is due to 210 Pb which has accumulated over 3 year operation.

13. Cost of CTF? (Vague numbers from peoples memory) 950 m 3 carbon steel tank ~$100,000 (~$100,000 in 1994). Tank liner $25,000. PMTs ~$250,000 ($2500ea with custom bases and support mounts). Frame $50,000 SS316 steel. Supporting clean room. Site preparation, water purification and recirculation system, electronics and DAQ.