NFerrari

ILIAS J1 MeetingWP1 Status Report and discussion: 

ILIAS J1 Meeting WP1 Status Report and discussion N. Ferrari (LNGS) J1 general meeting - Zaragoza, 11-12 July 2006

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J1-WP1 Review of objectives and general organization Status of the activities Neutrons Gamma background Radon Summary of next milestones Summary

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J1-WP1 : Review of objectives and general organization The main objective of J1-WP1 is to characterize the relevant backgrounds in the 4 Underground Labs: By collecting available existing data - By performing new, dedicated measurements The background components under study include: Neutrons Gamma rays Muons Radon The final deliverable will be a database containing information on old and new measurements of the background components.

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Status of the activities (from second annual report) In the case of Boulby, new gamma and radon measurements have been recorded by a group from Silesia University in a visit partially funded by a TARI program. At LNGS, measurements of the gamma background in various locations have been carried out with a 16 kg NaI detector, and a setup for a high statistics measurement of the fast neutron flux has been installed in hall A A complete program for the characterization of the new Canfranc Underground Laboratory has been developed. It started at the beginning of January (after the completion of the public works) and will continue during 2006. Radon monitoring continues in all laboratories; in the case of the Modane Laboratory a new system of radon purification by adsorption in charcoal is working since 2005

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A document has been created containing a list of all measurements. The document will be soon in the form of a real database and it will be continuously updated so that different users can look into it for information on new measurements and results on background.

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Neutrons

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A setup for a high statistics measurement of the fast neutron flux (energy range between 0.5 and 20 MeV) has been installed in hall A of the Gran Sasso National. Data taking started in the beginning of August 2005 New measurement of the spectrum and intensity of the neutron flux (fast component) in the LNGS underground laboratory. This activity is mainly focused on the evaluation of possible fluctuations with time of the neutron intensity. Identification of the physical correlation with other environmental parameters. Neutrons: LNGS new measurement

Overview: 

Overview February 2005 received first 2 litres BICRON cell June 2005 received second 2 litres BICRON cell July 2005 calibration with neutron beams at LNL July 2005 installation at LNGS hall A of electronics 1 litre cell 2 x 0.3 litres cells August 2005 installation of the second 2 litres cell September 2005 start of the data acquisitionc November 2005 installation at LNGS of a dedicated DAQ (0.2 l cell) for gamma background evaluation Marc 2006 installation of a lead shield (8 mm) to reduce the stochastic contribution induced by gamma background

First results: 

The energy distribution of selected data (p recoils) is then obtained using a detector calibration carried out by means of g-ray sources (eee Electron Equivalent Energy) and conversion factors (pee Proton Equivalent Energy). The energy distribution of neutrons is computed by means of a deconvolution program once the response function of the detector are known. With the installation of a lead shield, its sensitivity is now enough to perform, in few months of data taking, an evaluation of possible fluctuations with time of the neutron intensity. Preliminary results show the presence of variation of the counting rate beyond the statistical fluctuation above 3.5 MeV. Identification of the physical correlation with other environmental parameters, such as the rock moisture, ground water level and pressure, … is in progress. First results

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Two neutron background measurement systems have been developed and commissioned at Boulby: NUTs and DRIFT. Over 3 weeks of unshielded background data has been acquired and analysis is underway. Further data acquisition and analysis is planned in the coming months See presentation by Vitaly Neutrons: Boulby new measurement

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Gamma rays

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Gammas : measurements with movable Ge detector in all labs In August 2005 the IUS/Boulby hosted visitors from the University of Silesia, Poland carrying out a programme of Ge detector and Radon background measurements at European laboratories. The results were presented at the JRA1 general meeting in Paris, on February 14th. Furthermore, two gamma background measurement systems are under development at Boulby: a 2kg Ge and an encapsulated NaI detectors have been installed and commissioned in the low background laboratory. Measurements done in LNGS and Boulby, planned in LSC and LSM during 2006

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LNGS: a total number of 18 measurements of the gamma background in various locations inside LNGS have been carried out with a 16 kg NaI detector. Gammas : measurements at LNGS with movable NaI detector Calculation of absolute fluxes needed 15 kg portable NaI detector (LNGS)

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Muons

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Radon At LNGS, the Rn in the air of the lab is continuously monitored on-line and integrated on several months. It varies from approximately 50 Bq/m3 to 150 Bq/m3 in the ventilated areas, but it can reach 800-1000 Bq/m3 in non ventilated corners. The monitoring of the Rn is the water of the Gran Sasso massive is ongoing since several years. Time dependence of the signal is extremely interesting for geophysics At LSC, Rn is being monitored at all the experimental halls. Periodic measurements of radon concentration has been performed at different points. The results show a mean value of 64 Bq/m3 for the radon concentration in Hall A and 70 Bq/m3 in Hall B using two AlphaGuard PRO detectors. At Boulby, Rn measurements are less urgent than in other laboratories due to the low U, Th content. Typical levels are of the order of 5 Bq/m3. A RAD-7 radon detector is operational inside the low background laboratory. Other investigations of radon levels, radon-progeny plate-out / deposition and additional n-flux due to associated (α, n) reactions are planned in the near future. At LSM a new system of radon purification by adsorption in charcoal is working since 2005, the volume of clean air for this system is 125 m3/h and the activity of 222Rn is 15 mBq/m3. Please send some examples of Rn monitoring in the lab if available

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Next milestones