sPHENIX HCal discussion

[Stefan Bathe <bathe AT bnl.gov>]

Dear Edward, John, and Jamie,

Which book is that, Edward?  It would be nice to be able to look up the references.

For 100 GeV (just to stay with my earlier example) I get 6.2 lambda from the first and 7.2 lambda from the second formula.  They are not within 10 % of each other nor within 10 % of the measurements for Fe I quoted earlier.

I agree we won’t see 100 GeV jets in AuAu.  I had to pick one energy to compare the numbers, and the kinematic limit seemed to me a convenient upper limit.  For 70 GeV all numbers will be about 0.2 lambda smaller.

Regards,

Stefan

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Stefan Bathe

Professor of Physics
Baruch College, CUNY

Baruch:                                     BNL:
17 Lexington Ave                      Bldg. 510
office 940                                  office 2-229
phone 646-660-6272                phone 631-344-8490
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On Feb 5, 2018, at 6:29 PM, Edouard Kistenev <kistenev AT bnl.gov> wrote:

10% approximation always looked fine to me

<PastedGraphic-1.tiff>

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:

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[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

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[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

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[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

Baruch:                                     BNL:
17 Lexington Ave                      Bldg. 510
office 940                                  office 2-229
phone 646-660-6272                phone 631-344-8490
----------------------------------------------------------------------------------

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