[Hps-ecal] Opening angle from Ecal

[Holly Vance]

Hi Michel,

Thank you for your response. Indeed, you are correct-it is misleading to
write cluster energy since what I used was the thrown monte carlo energy.
FX sent me some suggestions for checking the residuals (phi_calc -
phi_generated), and the actual resolution will contain the spread from the
position and energy as measured. It is very nice to see that all of this
supports the plots from simulation in the HPS Note 2014-001.

Respectfully,
Holly

On Fri, Jan 9, 2015 at 6:17 AM, Garcon Michel <Michel.Garcon at cea.fr> wrote:

>  Hi Holly,
>
>
>
>                 Nice study. It is a bit counter-intuitive to call Phi a
> (projected) horizontal angle and Theta a vertical angle, but this is a
> minor detail.
>
>
>
>                 One does expect indeed dPhi/dx = dTheta/dx ~ 1/D ~ 1/1.4 m
> ~ 0.007 radian/cm . In the vertical projection, the trajectory is a
> straight line whatever the energy (for an ideal field), which explains that
> you find no energy dependence for Theta. In the horizontal projection, your
> line in the first plot Phi vs x at 1 GeV is the same as the light blue in
> Fig. 31 of HPS-Note-2014-001 (one can see also in this figure that the
> slope does not depend on energy). So everything checks nicely.
>
>
>
>                 I would expect B = 0 when E goes to infinity (straight
> line -> x = 0 when Phi =0). But you are right to do whatever empirical fit
> works in our range.
>
>
>
>
> Best regards,
>
>
> Michel.
>
>
>
> PS: by cluster energy, do you mean deposited energy in ECal or real
> energy? I would imagine the latter since you generate particles at fixed
> energies; then better not call it cluster energy, could be confusing (see
> Eqs 1 and 2 of the Note).
>
>
>
> *_______________*
>
> *Michel Garçon*
>
> *Irfu/SPhN                                               *
>
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>
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>
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