SLIDE 48 Electromagnetic calorimeters are well understood and
- ffer very precise energy measurement (e, γ detection)
48
“Hadron Calorimeters are usually far from ideal”
Hadron Shower
11
- H. Brfickmann et al. / Hadron sampling calorimetry
139
e m~p
1,0 0,g 0,8 0,7 0,6 0,5 O,A 0,3 0,2 0,1
Fe {/~ rnrn ) Cu
Fe
(5ram) [5 rtlm) Pb 25mm Pb Pb I zmnn} 12~ rnm) , m
c i n t i t t a t
E G S
3 ,
1 G e V
(standard cuts, defautt step size) (~)exp 1,3 1,& 1,5 1,7 1.8 2,0
~
r
t
r i r a 1 , I i /
2 z, 6 8 10 12 [mm] absorber thickness
krnip
e
1, 20 1,36
11,44
2,o
- Fig. 4. e/mip ratios for various absorber and scintillator
- thicknesses. A slight dependence of e/nip with the scintillator
thickness is revealed. The open circles give the result for cladding the absorber sheets (2x0.4 mm Cu for the 3 mm U-sheet and 2×1 mm Fe for the 10 mm U-sheet). The zx symbol belongs to an EGS calculation, using nonstandard cuts (ECUT = 0.711 MeV, AE = 0.700 MeV and PCUT = AP = O.1 MeV) and a step size parameter ESTEPE = 0.5%. On the right scale, the mip/e-ratio is compared to an (v/e)cxp ratio ex- pected for 10 GeV muons.
e.
rn1~
%0
0,9 0,8 0.7
O, 6
0,5 0,4 0,3 0.2 0,1
ClA
(3mml
Pb
(Smm}
~ m,,, l u
5mmJ
L i q u i d A r g
( L A )
E G S 3 , 1 G e V
(standard cuts, defaul, t step size) nip ( e'Pe-)e x
e
1A -~ 1,05 1,6- 1,2 Pb
(~mm) 2- 1,5
24. 1,8 4,0- 3,0
I i
1 2 [ m m
I I I I I f , I i I I
2 4 6 8 10
absorber thickness
- Fig. 5. The e/mip ratios for liquid argon detector layers and
various absorber materials. By comparing with fig. 4, one
- bserves that the higher Z material (LA) increases the e/mip
- ratio. This is due to a photon detection efficiency which
increases with the Z of the detector layer. On the right scale, the mip/e ratio is compared to an (#/e)e.p ratio expected for 10 GeV muons. either by spallation of high Z nuclei or - in case of fissionable material - be evaporated from the highly excited fission products. The few very highly energetic neutrons created will travel some distance through the stack and then indicate a further spallation. They be- have rather similarly to the charged highly energetic hadrons. Most of the neutrons are created in an energy range between 0.1 and 10 MeV by nuclear evaporation. The spectra and the method of calculation are discussed in section 2. For understanding the response to neutrons in a sampling structure, one has to consider their mean free path. Fig. 7 illustrates the total cross section of natural uranium, the fission cross section of 238U, the (n, 7) capture cross section of 23Su and the n-p elastic cross section in the energy range from 10 keV to 100
- MeV. The neutron mean free path ranges between 2 and
5 cm typically, as can be evaluated from the cross sections and a weighted material composition. There- fore in the energy range considered, neutrons are not
lionization primary
loss i
secondary , interaction ,mteract,ons ot the same kind hadton I "fi't /n IntranucLear cascade high emergetic part C es within one r~ucteusJ~ are summarized in the (SpatLatlon) "Inter - Nuclear Cascade" The highly excited nucLei might el lher evaporate
many paeticles fission process
- Fig. 6. Step I: Development of an "internuclear cascade".
From one nucleus an intranuclear cascade releases a few high energetic spallation products, which are able to iniciate further intranuclear cascade processes. Step II: The highly excited nuclei remaining from each intranuclear cascade deexcite.
NIM A 263 (1988) 136
Spallation
Step I Step II
11 Thursday, October 24, 13
