sPHENIX HCal discussion

[Edouard Kistenev <kistenev AT bnl.gov>]

10% approximation always looked fine to me

On Feb 5, 2018, at 3:23 PM, Stefan Bathe <bathe AT bnl.gov> wrote:

Dear All,

I find some inconsistencies with how many nuclear interaction lengths (lambda) are required to contain 95 % of the energy of a hadronic shower (L(95%)):

1) The CDR says 

L(95%) > 5.5 lambda 

in the introductory section of the HCal.  No energy is quoted.  So let’s assume 100 GeV pions as proxies for jets at kinematic limit for RHIC HI.

2) [WI00] (Fig 2.37, attached) gives 

L(95%) @ 100 GeV = 6.0 lambda

N.B.:  the reference is [AB81]!

3) [AB81] gives 

L(95%) @ 100 GeV: 87.5 cm Fe = 5.15 lambda (table 4)

contradicting Wigmans!

4) [HO78b] gives 

L(95%) @ 100 GeV: 82 cm Fe = 4.8 lambda (Fig. 10)

5) [KL91] gives

L(95%) @ 100 GeV: 82 cm Fe = 4.8 lambda (parameterization)

I’m inclined to dismiss Wigmans since the plot misrepresents the quoted reference.  Does anybody have better information?  Or maybe I’m misunderstanding something?

Regards,

Stefan

references:

—

[WI00] Wigmans, Calorimetry, Oxford, 2000” (p. 87, Fig. 2.37)

(see attachment)

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[HO78b] M.Holder et al., Nucl.Instr.Meth.,151,69 (1978),
Performance of a Magnetized Total Absorption Calorimeter Between 15-GeV and 140-GeV
5 cm Fe sampling
L(95%) @ 100 GeV: 82 cm Fe = 4.8 lambda (from plot with data points and fit in paper; or parameterization in Kleinknecht textbook)

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwju8M2mxY_ZAhWHyoMKHTAyAgQQFgg_MAQ&url="http%3A%2F%2Fcds.cern.ch%2Frecord%2F879171%2Ffiles%2Fep113_001.pdf&usg=AOvVaw18tk97fLX9RJZVIoNU1SVM

---

[AB81] Nucl.Instr.Meth.,180,429 (1981) 
The response and resolution of an iron-scintillator calorimeter for hadronic and electromagnetic showers between 10 GeV and 140 GeV
2 cm Fe sampling
L(95%) @ 100 GeV: 87.5 cm Fe = 5.15 lambda (table)
comments:
- interaction required in first 37.5 cm of iron; possible bias
- referenced in Wigmans, but I cannot reproduce Wigmans plot from data in paper

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwjRoonEyI_ZAhVs4YMKHd-dCaUQFghTMAc&url="https%3A%2F%2Fcds.cern.ch%2Frecord%2F134124&usg=AOvVaw0ZxhJB8UKofvCs-ni1UPaX

—

[KL92] "Kleinknecht, Detektoren fuer Teilchenstrahlung, Teubner, 1992”, I find the following parameterization:
L(95%) = [9.4 ln E(GeV) + 39] cm Fe.  With lambda = 17.1 cm (Fe)

also references [BL82] H. Bluemer, Diplomarbeit Dortmund, 1982

<Wigmans2.37.JPG>

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Stefan Bathe

Professor of Physics
Baruch College, CUNY

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