428
A. Ariga et al.
to light dark matter shows to be very competitive with all the planned experiments
in the next decade.
The SHiP Collaboration is preparing a Comprehensive Design Report to be
submitted within 2018, in the framework of the Physics Beyond Colliders working
group, that will be evaluated within 2020. The construction and installation is
expected to start in 2021 with data taking to start in 2026.
9.6.3 Projects in Applied Science
9.6.3.1 Muon Radiography
Muon radiography measures the absorption of cosmic-ray muons in matter, analogously to the conventional radiography that makes use of X-rays. The interaction
of primary cosmic-rays with the atmosphere provides an abundant source of muons
that can be used for various applications of muon radiography. Muon radiography
was first proposed to determine the thickness of snow layers on a mountain [174].
The first application was realised in 1971 with the seminal work of Alvarez and
collaborators searching for unknown burial cavities in Chephren’s pyramid [175].
The pioneering work done in Japan for the radiography of the edifice of volcanoes
by using quasi-horizontal cosmic-ray muons [176, 177] has opened new possibilities
for the study of their internal structure.
Nuclear emulsions were used for the first time in 2006 for the muon radiography
of the Asama volcano in Japan [178]. The main advantages of the emulsion
technique are the simplicity and portability of the detector setup, and the absence of
power supplies and electronic data acquisition systems, usually difficult to transport
and operate on the summit of a volcano.
In 2012 an emulsion detector was installed on the Stromboli volcano to image its
crater region. Despite of the strong influence that the crater area and the Sciara
del Fuoco slope have on the volcanic dynamics of the Stromboli island, their
internal structure is not well known because of the limited resolution of conventional
geophysical methods. An emulsion detector of 0.73 m 2 surface was exposed there
and took data for about 5 months in 2012. Emulsion films were exposed in the form
of two doublets separated by 5 mm iron slabs intended to reject the background
induced by the soft component of cosmic-rays. Figure 9.31 shows an excess in the
rate of muons in the crater region that is interpreted in terms of a lower density
region [179]. This excess lies in the region B of Fig. 9.31, the one where the detector
is sensitive to density variations, while A denotes the free sky region. In the region
C, instead, the average thickness is larger than 800 m, such that the rate is too low
to appreciate density changes. The data analysis provided an image of the crater
area of Stromboli with a resolution of about 10 m in the center of the target area.
The observed muon excess larger than 30% indicates an average density decrease
along the muon path down to 1.7 g/cm 3 with respect to the standard rock density
A. Ariga et al.
to light dark matter shows to be very competitive with all the planned experiments
in the next decade.
The SHiP Collaboration is preparing a Comprehensive Design Report to be
submitted within 2018, in the framework of the Physics Beyond Colliders working
group, that will be evaluated within 2020. The construction and installation is
expected to start in 2021 with data taking to start in 2026.
9.6.3 Projects in Applied Science
9.6.3.1 Muon Radiography
Muon radiography measures the absorption of cosmic-ray muons in matter, analogously to the conventional radiography that makes use of X-rays. The interaction
of primary cosmic-rays with the atmosphere provides an abundant source of muons
that can be used for various applications of muon radiography. Muon radiography
was first proposed to determine the thickness of snow layers on a mountain [174].
The first application was realised in 1971 with the seminal work of Alvarez and
collaborators searching for unknown burial cavities in Chephren’s pyramid [175].
The pioneering work done in Japan for the radiography of the edifice of volcanoes
by using quasi-horizontal cosmic-ray muons [176, 177] has opened new possibilities
for the study of their internal structure.
Nuclear emulsions were used for the first time in 2006 for the muon radiography
of the Asama volcano in Japan [178]. The main advantages of the emulsion
technique are the simplicity and portability of the detector setup, and the absence of
power supplies and electronic data acquisition systems, usually difficult to transport
and operate on the summit of a volcano.
In 2012 an emulsion detector was installed on the Stromboli volcano to image its
crater region. Despite of the strong influence that the crater area and the Sciara
del Fuoco slope have on the volcanic dynamics of the Stromboli island, their
internal structure is not well known because of the limited resolution of conventional
geophysical methods. An emulsion detector of 0.73 m 2 surface was exposed there
and took data for about 5 months in 2012. Emulsion films were exposed in the form
of two doublets separated by 5 mm iron slabs intended to reject the background
induced by the soft component of cosmic-rays. Figure 9.31 shows an excess in the
rate of muons in the crater region that is interpreted in terms of a lower density
region [179]. This excess lies in the region B of Fig. 9.31, the one where the detector
is sensitive to density variations, while A denotes the free sky region. In the region
C, instead, the average thickness is larger than 800 m, such that the rate is too low
to appreciate density changes. The data analysis provided an image of the crater
area of Stromboli with a resolution of about 10 m in the center of the target area.
The observed muon excess larger than 30% indicates an average density decrease
along the muon path down to 1.7 g/cm 3 with respect to the standard rock density