Study of the interactions of pions in the CALICE silicon-tungsten calorimeter prototype
- Adloff, C. et al
- arXiv:1004.4996CALICE-CAN-2010-001CALICE Analysis Note CAN-020CALICE-PUB-2010-002
 | \em Schematic layout for the CALICE beam tests at CERN in 2007 (not to scale).Dimensions are indicated in mm. |
 | \em Example of the beam profiles in $x$ and $y$ (based on the shower centroid reconstructed in the ECAL) observed with a 20~GeV $\pi^-$ beam. Data (points with error bars) are compared with the tuned simulation (solid histogram).The distributions are normalised to the same numbers of events. |
 | \em Showing the principle of the cuts used to remove muons and non-interacting hadrons. The energies in the three calorimeters (in MIPs) are plotted for a 20~GeV data run. The three stacks in the ECAL are combined using weights proportional to thecorresponding thicknesses of tungsten, i.e.\ 1:2:3. |
 | \em Energy observed in the ECAL for events with and without a signal from the beam \v{C}erenkov counter. For this plot, the observed energy was converted from MIPS to GeV using a nominal conversion factor of 240 MIPs/GeV. (a) In the case of the 12~GeV negatively charged beam, the open region shows the total sample, and the shaded region the contribution with no \v{C}erenkov signal. (b) For the 30~GeV positively charged beam the shaded histogram shows triggers witha \v{C}erenkov signal, and the open (red) histogram shows those with no \v{C}erenkov signal. |
 | \em Energy observed in the ECAL for events with and without a signal from the beam \v{C}erenkov counter. For this plot, the observed energy was converted from MIPS to GeV using a nominal conversion factor of 240 MIPs/GeV. (a) In the case of the 12~GeV negatively charged beam, the open region shows the total sample, and the shaded region the contribution with no \v{C}erenkov signal. (b) For the 30~GeV positively charged beam the shaded histogram shows triggers witha \v{C}erenkov signal, and the open (red) histogram shows those with no \v{C}erenkov signal. |
 | \em Mean fraction of non-interacting pions (energy $<$100 MIPs) in the ECAL, plotted as a function of beam energy. For this purpose, the three ECAL stacks were combined with weights 1:1:1. The data are compared with the predictions of simulations using different {\tt GEANT4} physics lists. The models are separated into two plots in the interests of clarity,with the physics lists which incorporate the Bertini model on the left, and the others on the right. |
 | \em Distributions of total energy recorded in the ECAL at 8, 15, 30 and 80~GeV (points with error bars), compared with Monte Carlo predictions using the QGSP\_BERT physics list (solid histograms). The distributions are normalised to the same numbers of selected events(including the non-interacting peak). |
 | \em Distributions of total energy recorded in the ECAL at 8, 15, 30 and 80~GeV (points with error bars), compared with Monte Carlo predictions using the QGSP\_BERT physics list (solid histograms). The distributions are normalised to the same numbers of selected events(including the non-interacting peak). |
 | \em Distributions of total energy recorded in the ECAL at 8, 15, 30 and 80~GeV (points with error bars), compared with Monte Carlo predictions using the QGSP\_BERT physics list (solid histograms). The distributions are normalised to the same numbers of selected events(including the non-interacting peak). |
 | \em Distributions of total energy recorded in the ECAL at 8, 15, 30 and 80~GeV (points with error bars), compared with Monte Carlo predictions using the QGSP\_BERT physics list (solid histograms). The distributions are normalised to the same numbers of selected events(including the non-interacting peak). |
 | \em Ratio of simulation to data for the mean energy recorded in the ECAL, plotted as a function of beam energy.The data are compared with the predictions of simulations using different {\tt GEANT4} physics lists. |
 | \em Radial distribution of hits (energy weighted) for data at four typical energies (points with errors) compared with Monte Carlo (solid histograms)using the {\tt QGSP\_BERT} physics list. The distributions are normalised to unity. |
 | \em Radial distribution of hits (energy weighted) for data at four typical energies (points with errors) compared with Monte Carlo (solid histograms)using the {\tt QGSP\_BERT} physics list. The distributions are normalised to unity. |
 | \em Radial distribution of hits (energy weighted) for data at four typical energies (points with errors) compared with Monte Carlo (solid histograms)using the {\tt QGSP\_BERT} physics list. The distributions are normalised to unity. |
 | \em Radial distribution of hits (energy weighted) for data at four typical energies (points with errors) compared with Monte Carlo (solid histograms)using the {\tt QGSP\_BERT} physics list. The distributions are normalised to unity. |
 | \em Mean energy-weighted shower radius in the ECAL as a function of beam energy.The data are compared with the predictions of simulations using different {\tt GEANT4} physics lists. |
 | \em Radii required to contain 90\% (upper two plots) or 95\% (lower two plots) of the energy seen in the ECAL, as a function of beam energy.Data are compared with simulation for various physics lists. |
 | \em Radii required to contain 90\% (upper two plots) or 95\% (lower two plots) of the energy seen in the ECAL, as a function of beam energy.Data are compared with simulation for various physics lists. |
 | \em Left: comparison between reconstruction and truth for the layer identified as the interaction layer by the algorithm described in the text. This example corresponds to a 20~GeV $\pi^-$ beam simulation, using the QGSP\_BERT physics list. The grey scale indicates the number of events in each bin, where bins containing fewer than 10 events (amongst a total of more than 23000) have been suppressedfor the sake of clarity. Right: distribution of (reconstructed $-$ true) layer for this sample. |
 | \em Left: comparison between reconstruction and truth for the layer identified as the interaction layer by the algorithm described in the text. This example corresponds to a 20~GeV $\pi^-$ beam simulation, using the QGSP\_BERT physics list. The grey scale indicates the number of events in each bin, where bins containing fewer than 10 events (amongst a total of more than 23000) have been suppressedfor the sake of clarity. Right: distribution of (reconstructed $-$ true) layer for this sample. |
 | \em Distribution of the reconstructed interaction layer in the ECAL for 30~GeV data (points), compared with Monte Carlo predictions using the QGSP\_BERT physicslist (solid histogram). |
 | \em Energy per layer in the ECAL for 10~GeV electron data (points),compared with Monte Carlo predictions (solid histogram). |
 | \em Longitudinal energy profiles for 12~GeV $\pi^-$ data (shown as points), compared with simulations using different physics lists. The mean energy in MIPs is plotted against the depth after the initial interaction, in units of effective 1.4~mm tungsten layers. The total depth shown corresponds to $\sim20\;X_0$ or $0.8\;\lambda_{\mathrm{int.}}$. The breakdown of the Monte Carlo into the energy deposited by different particle categoriesis also indicated. |
 | \em Longitudinal energy profiles for data (shown as points) compared with simulations using two physics lists, {\tt QGSP\_BERT} and {\tt FTFP\_BERT}, at four typical energies. The breakdown of the Monte Carlo into the energy deposited by different particle categoriesis also indicated. |
 | \em Ratio of simulation to data for three different regions of the longitudinal energy profile: (top pair of plots) layers 1-3, dominated by nuclear breakup; (centre pair) layers 5-20, dominated by electromagnetic showers;and (bottom pair) layers 30-50, dominated by penetrating hadrons. |
 | \em Ratio of simulation to data for three different regions of the longitudinal energy profile: (top pair of plots) layers 1-3, dominated by nuclear breakup; (centre pair) layers 5-20, dominated by electromagnetic showers;and (bottom pair) layers 30-50, dominated by penetrating hadrons. |
 | \em Ratio of simulation to data for three different regions of the longitudinal energy profile: (top pair of plots) layers 1-3, dominated by nuclear breakup; (centre pair) layers 5-20, dominated by electromagnetic showers;and (bottom pair) layers 30-50, dominated by penetrating hadrons. |