The interaction of
K
-
with protons is characterised by the presence of several coupled channels, systems like
K
¯
0
n and
π
Σ
with a similar mass and the same quantum numbers as the
K
-
p state. The ...strengths of these couplings to the
K
-
p system are of crucial importance for the understanding of the nature of the
Λ
(
1405
)
resonance and of the attractive
K
-
p strong interaction. In this article, we present measurements of the
K
-
p correlation functions in relative momentum space obtained in pp collisions at
s
=
13
Te, in p–Pb collisions at
s
NN
=
5.02
Te, and (semi)peripheral Pb–Pb collisions at
s
NN
=
5.02
Te. The emitting source size, composed of a core radius anchored to the
K
+
p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the
K
¯
0
n and
π
Σ
inelastic channels on the measured
K
-
p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights
ω
, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured
K
-
p interaction indicates that, while the
π
Σ
–
K
-
p dynamics is well reproduced by the model, the coupling to the
K
¯
0
n channel in the model is currently underestimated.
Particle computed tomography (pCT) is an emerging imaging modality that promises to reduce range uncertainty in particle therapy. The Bergen pCT collaboration aims to develop a novel pCT prototype ...based on the ALPIDE monolithic CMOS sensor. The planned prototype consist of two tracking planes forming a rear tracker and Digital Tracking Calorimeter (DTC). The DTC will be made of a 41 layer ALPIDE-aluminum sandwich structure. To enable data acquisition at clinical particle rates, a large multiplicity of particles will be measured using the highly-granular ALPIDE sensor. In this work, a first characterization of the ALPIDE sensor performance in ion beams is conducted. Particle hits in the ALPIDE sensor result in charge clusters whose size is related to the chip response and the particle energy deposit. Firstly, measurements in a 10 MeV 4He micro beam have been conducted at the SIRIUS microprobe facility of ANSTO to investigate the dependence of the cluster size on the beam position over the ALPIDE pixel. Here, a variation in cluster size depending on the impinging point of the beam was observed. Additional beam tests were conducted at the Heidelberg Ion-Beam Therapy Center (HIT) investigating the cluster size as a function of the deposited energy by protons and 4He ions in the sensitive volume of the ALPIDE. Results show the expected increase in cluster sizes with deposited energy and a clear difference in cluster sizes for protons and 4He ions. As a conclusion, the variation in cluster size with the impinging point of the beam has to be accounted for to enable accurate energy loss reconstruction with the ALPIDE. This does, however, not affect the tracking of particles through the final prototype, as for that only the center-of-mass of the cluster is relevant.
A novel approach for designing the next generation of vertex detectors foresees to employ wafer-scale sensors that can be bent to truly cylindrical geometries after thinning them to thicknesses of ...20–40 μm. To solidify this concept, the feasibility of operating bent MAPS was demonstrated using 1.5cm×3cm ALPIDE chips. Already with their thickness of 50µm, they can be successfully bent to radii of about 2cm without any signs of mechanical or electrical damage. During a subsequent characterisation using a 5.4GeV electron beam, it was further confirmed that they preserve their full electrical functionality as well as particle detection performance.
In this article, the bending procedure and the setup used for characterisation are detailed. Furthermore, the analysis of the beam test, including the measurement of the detection efficiency as a function of beam position and local inclination angle, is discussed. The results show that the sensors maintain their excellent performance after bending to radii of 2cm, with detection efficiencies above 99.9% at typical operating conditions, paving the way towards a new class of detectors with unprecedented low material budget and ideal geometrical properties.
A typical proton CT (pCT) detector comprises a tracking system, used to measure the proton position before and after the imaged object, and an energy/range detector to measure the residual proton ...range after crossing the object. The Bergen pCT collaboration was established to design and build a prototype pCT scanner with a high granularity digital tracking calorimeter used as both tracking and energy/range detector. In this work the conceptual design and the layout of the mechanical and electronics implementation, along with Monte Carlo simulations of the new pCT system are reported. The digital tracking calorimeter is a multilayer structure with a lateral aperture of 27 cm × 16.6 cm, made of 41 detector/absorber sandwich layers (calorimeter), with aluminum (3.5 mm) used both as absorber and carrier, and two additional layers used as tracking system (rear trackers) positioned downstream of the imaged object; no tracking upstream the object is included. The rear tracker’s structure only differs from the calorimeter layers for the carrier made of ∼200 μm carbon fleece and carbon paper (carbon-epoxy sandwich), to minimize scattering. Each sensitive layer consists of 108 ALICE pixel detector (ALPIDE) chip sensors (developed for ALICE, CERN) bonded on a polyimide flex and subsequently bonded to a larger flexible printed circuit board. Beam tests tailored to the pCT operation have been performed using high-energetic (50–220 MeV/u) proton and ion beams at the Heidelberg Ion-Beam Therapy Center (HIT) in Germany. These tests proved the ALPIDE response independent of occupancy and proportional to the particle energy deposition, making the distinction of different ion tracks possible. The read-out electronics is able to handle enough data to acquire a single 2D image in few seconds making the system fast enough to be used in a clinical environment. For the reconstructed images in the modeled Monte Carlo simulation, the water equivalent path length error is lower than 2 mm, and the relative stopping power accuracy is better than 0.4%. Thanks to its ability to detect different types of radiation and its specific design, the pCT scanner can be employed for additional online applications during the treatment, such as in-situ proton range verification.
EUDAQ is a generic data acquisition software developed for use in conjunction with common beam telescopes at charged particle beam lines. Providing high-precision reference tracks for performance ...studies of new sensors, beam telescopes are essential for the research and development towards future detectors for high-energy physics. As beam time is a highly limited resource, EUDAQ has been designed with reliability and ease-of-use in mind. It enables flexible integration of different independent devices under test via their specific data acquisition systems into a top-level framework. EUDAQ controls all components globally, handles the data flow centrally and synchronises and records the data streams. Over the past decade, EUDAQ has been deployed as part of a wide range of successful test beam campaigns and detector development applications.
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