We have developed and upgraded portable 950 keV/3.95 MeV X-band (9.3 GHz) linac x-ray sources for on-site nondestructive testing (NDT) for social and industrial infrastructures. We integrated the hardware devices as well as software systems. For the hardware, we established all designed parameters including x-ray intensities of 0.05/2 Gy min −1 at 1 m for 950 keV/3.95 MeV systems, respectively. Concerning the software, we adopted the wavelet analysis for enhanced image contrast and partial angle computed tomography (CT) for a small region of interest. The wavelet analysis is effective to reduce scattered low energy x-ray noise in addition to using physical filters and collimators. The partial CT is inevitable to reconstruct an inner reinforced iron tube in concrete. We successfully performed on-site inspection three times, namely of a nitrogen acid distillation tower, a reinforced concrete pier and a large sample cut from a bridge. We obtained the x-ray images of the inner tube, determined the sizes of reinforced iron parts and evaluated the mechanical tolerance. Moreover, we are developing a new x-ray camera specified for MeV x-rays used for NDT of heavy objects. Then, our system will become a self-consisting and specialized high energy x-ray on-site inspection system. We are going to promote an application to NDT of social and industrial infrastructures in Japan and around the world.

The temporal signals from a large gas detector may show dynamical scaling due to many correlated space points created by the charged particles while passing through the tracking medium. This has been demonstrated through simulation using realistic parameters of a Time Projection Chamber (TPC) being fabricated to be used in ALICE collider experiment at CERN. An interesting aspect of this dynamical behavior is the existence of an universal scaling which does not depend on the multiplicity of the collision. This aspect can be utilised further to study physics at the device level and also for the online monitoring of certain physical observables including electronics noise which are a few crucial parameters for the optimal TPC performance.Dynamical scaling refers here to powerlaw distribution or a powerlaw with an exponential cut-off that describes certain correlation phenomena in the dynamical systems distinctly being different from the random statistical processes. In the thermodynamical context, it describes a critical phenomena associated with the phase transition [1] while in many other complex systems it corresponds to the so called self organised criticality [2]. Although a powerlaw distribution (f ∼ x −β ) is a common dynamical feature, a powerlaw with an additional exponential (f ∼ x −β e −αx ) makes the distribution normalizable for all values of β (where α and β are positive constants) and also many real world systems like World Wide Web and social networks show this cut-off [3]. In this paper, we show the presence of both type of scalings, a powerlaw and a powerlaw with exponential in the temporal signals (comprising of time gap and bunch length distributions) of a large Time Projection Chamber (TPC) which is a type of gas detector used for three dimensional tracking of the charged particles passing through it during a particle physics experiment. The time gap distribution along the drift direction shows a dynamical scaling which is independent of the multiplicity of the collisions above a critical value. While this scaling behavior itself is an interesting aspect to investigate the correlation phenomena in a gas detector at the device level, it can be further utilised for online monitoring of certain important TPC parameters including the constant rise in electronics noise level due to long exposure to radiation.The TPC is the main tracking device of the ALICE (A Large Ion Collider Experiment) [4] at the Large Hadron Collider (LHC) at CERN optimized for the study of heavy ion collisions at a centre of mass energy ∼ 5.5 ATeV. It is a large gas filled detector of cylindrical design with an inner radius of about 80 cm, an outer radius of about 250 cm, and an over all length in the beam direction of 500 cm. A charged particle passing through the gas volume creates electrons by ionization. The electrons drift in the electric field towards the read out chambers (multiwire proportional counters with more than 550000 cathode pads read out located at the two end-caps of the TPC cylinder) where they are amplifie...

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Regular diagnosis of the structural health of infrastructure, such as bridges, is indispensable to ensure safety and reliable operation of the society. Non-destructive tests based on X-ray imaging are powerful tools to inspect the inside of a concrete structure in detail. Establishing a diagnostic method of bridges based on X-ray visualization is required to examine the internal conditions and helps in the rationalization of maintenances. We demonstrated our 950 keV X-band electron linac based X-ray source for on-site actual bridge inspection and visualized the inner structure of a bottom floor slab. For the more precise inspection of the conditions of wires and rods, we applied three-dimensional image reconstruction methods for bridge mock-up samples. Partial angle computed tomography and tomosynthesis gave cross section images of the samples with 1 mm resolution. We are planning to investigate another part of the bridge, with the 950 keV X-ray system in the near future.

Many bridges around the world face aging problems and degradation of structural strength. Visual and hammering sound inspections are under way, but the status of inner reinforced iron rods and prestressed concrete (PC) wires has not yet been confirmed. Establishing a diagnosis method for bridges based on X-ray visualization is required to evaluate the health of bridges accurately and to help with the rationalization of bridge maintenance. We developed 950 keV/3.95 MeV X-band electron linac-based X-ray sources for on-site bridge inspection and visualized the inner structure of a lower floor slab. The information regarding wire conditions by X-ray results was used for the structural analysis of a bridge to evaluate its residual strength and sustainability. For more precise inspection of wire conditions, we applied three-dimensional image reconstruction methods for bridge mock-up samples. Partial-angle computed tomography (CT) and tomosynthesis provided cross-sectional images of the samples at 1 mm resolutions. Image processing techniques such as the curvelet transform were applied to evaluate diameter of PC wires by suppressing noise. Technical guidelines of bridge maintenance using the 950 keV/3.95 MeV X-ray sources are proposed. We plan to offer our technique and guidelines for safer and more reliable maintenance of bridges around the world.