Hadron energy
measurement in thesampling calorimeter
Tohru Takeshita (Shinshu Univ.)
for CALOR2014 @ Giessen

event by event basis analysis
with ﬁne samplings

Hadron measurement• H interaction length ~10cm>> X0 ~1cm radiation
length for EM interaction

localized• once a pi-zero produced
EM shower emerges EEM>>Epi+-• nuclear interactions
and neutrons• photons
eprotonevaporation / spallation

EM shower

experimental data

8 GeV

0.08

0.02
12

3

45

• JINST 8,2013, P07005z [!I]

31.5

45

CALICE Fe-AHCAL
18 GeVDATAsystFTFP_BERTe+e%p1

QGSP_BERTQGSP_FTFP_BERTCALICE Fe-AHCAL
QBBC
syst

0.5

MC / DATA

12z [!I]

0.04
0.02

8GeV

0.04

CALICE Fe-AHCAL

0.06

CALICE Fe-AHCAL

0.06

DATA
syst
FTFP_BERT
e+e%
p0.1

DATA
syst
FTFP_BERT
e+e%
p0.1

0.08

MC / DATA$ Erec # [MIP] / " !I

FTFP̲Bert model Geant408 GeV

0.12• (Fe20mm+sc.5mm) x 40layers• pions incident: 8 & 18GeV• longitudinal shower proﬁle : z• (1) electrons from π• (2) protons• (3) charged pions ~ MIP
0.12$ Erec # [MIP] / " !ICALICE AHCAL

0118GeV2345z !int
1.5

1

CALICE Fe-AHCAL

23depth from shower
start point

145z [!I]event data
• CALICE AHCAL events• without selection
spikespike

32GeV pilayer {(e)*(nevt==10002)}
mips
htemp
Entries
364
Mean
21.61
RMS
6.265

layer {(e)*(nevt==10001)}

mips

120
100
80
60

Temperature sensors placed inside the detector in correspondence to each modu
temperature changes with an accuracy better than 0.6 ◦ C .
htemp

EntriesMean
502.3 The TCMTRMS
The TCMT is positioned downstream with respect to the AHCAL in order to absorb theshowers leaking out of the AHCAL. The TCMT has a lateral size of 109 × 109 cm2 and40in depth, corresponding to 5.8 !I . It consists of two sections, a fine one and a coarse
section has 8 sensitive layers, alternating with steel absorbers. The absorber plates are 2 c
the fine section and 10 cm thick in the coarse section. The sensitive layers are 0.5 cm thisegmented into 5 cm wide and 1 m long scintillator strips, with alternating horizontal a30
orientation in adjacent layers. The scintillation light is collected by WLS fibers and dSiPMs, as for the AHCAL prototype.

203 Calibration

402000iron20mm+sci5mm

Figure 2. Left: segmentation of a sensitive layer of the AHCAL. The size of the scintillator tile
towards the outer region. Right: schematic view of the active layers of the AHCAL.

510152025303540layer

layer num.

As typical of semiconductor devices, SiPMs are sensitive to temperature and bias voltag
10that affect most of their performance parameters [7]. Moreover, SiPMs show saturation eto the finite number of pixels and the finite pixel recovery time. One of the main technic
the AHCAL prototype is to show that these effects can be handled over a large number of
0 The calibration chain is described in [9]. It proceeds through the following steps:

05101520253035• inter-cell equalization of the response;layer num.

• calibration of the SiPM signal and correction for the non-linear response;layerevent by event• simulation : longitudinally ﬁnesegmented calorimeter• QGSP̲BERT• found spikes• high dE in a layer• due to protons

dE/layer(MIP)

lead20mm+sci5mm

5GeV πa proton
3 green ; proton
7 air-blue: heavy ion
2 red ; electrons
4 blue : pi+-layer num.

a spike in H-int.

• an event• positive charged recoil• proton from np>pn• spallation neutron• timing ~0• Tn~Tp~50MeV

spallation neutron

blue track is positively chargedFesci.

green tracks are neutrals

dE vs layer• simulation dE/

lead20mm+sci5mm• QGSP̲BERT• protoncontribution• makes spikes

klayerdE/layer(MeV)

5GeV πenergy deposit /layer
1 color code
3 green ; proton
37green; proton
air-blue:
heavy
7ion
air-blue: heavy ion
22redred; ;electron
electrons
44blueblue: :pi+pi+-

proton energies
cut applied•E
5GeV π• most of spikes are low E from spallation
lead20mm+sci5mm

protonEsum in a event for particles

Eproton>1125MeV
energy deposit / layer
1 total3 green ; proton
7 air-blue: heavy ion
2 red ; electrons
4 blue : pi+-

Esum (MeV~MIP) Tp>200MeV

Esum (MeV)spikes in liq./gas• liq. Ar has spikes: spallation protons
5GeV πnospikes
ingas
detector•Fe25+gasAr5

Pb10+LiqAr5

Energy Deposit in layer

EdeEntries
MeanRMS

Edep
Entries
100
0.14
Mean
19.89
RMS
13.12
deposit Energy/ev/l [MeV]

deposit Energy/ev/l [MeV]

Energy Deposit in layer
40353025

energy deposit /layer
1 color code
3 green ; proton
7 air-blue:
heavy ion
2 red ; electrons
4 blue : pi+-0.12
0.1
0.08

200.06150.04100.02

500102030405060

layer num.

7080

00 10090
Layer Number

1020304050

layer num.

60708090
1Layer Numberhow to avoid spikes• a 5GeV pion event : 3 spikes EMshower atfrom proton Pb10+sc5mm
an event~mips

1 total3 green ; proton
7 air-blue: heavy ion
2 red ; electrons
4 blue : pi+-layer=30

red~Nphotons in abs. layer
EM shower indicator
scintillator layer

layer num.

Cerenkov light• EM shower
detection inabsorber• utilizing

5GeV pi- into Pb10+sc5 HCAL~num. Cerenkov photon

Cerenkovlight det.

• goodcorrelationprob. lowdE in scintillator

summary & outlook• hadrons make spikes in the an event
sampling calorimeter• by low energy protons• makes large ﬂuctuation in~mips

due to Bragg peakenergy measurement• to avoid them, Cerenkov inabsorber can help

• need to develop technique

to measure in sampling CAL.

Nlayerspike rejection• spikes could be avoided by• ﬁne lateral segmentation• localized in a small unit
• ﬁnd & remove a spike hit• little eﬀect to total energy
measurement