Hi Chi,
Thank you for the update. I am sorry to hear you have a cold. Would it be
possible to participate in to-moorrow's meeting by speakerphone? I do
think it
is important to have as many BLAST collaborators as possible participating in
the weekly analysis meeting, particularly central players like yourself. I
hope you feel better soon.
regards,
Richard
Quoting Chi Zhang <zhangchi@MIT.EDU>:
>
> Hi
>
> I m having a pretty bad cold so would like to be excused tomorrow.
> but I do have answers for a couple questions raised.
>
>> +Verification of material budget
> this is not an answer, but I have no problem betting my money on
> Aaron's implemetation of the materials knowing him personally.
>
>> +Does reconstruction of MC with all switches off reproduce input?
>
> yes ofcourse. this is the case since the reconstruction first started
> running in 2001? and has been true ever since, maybe only except a
> period of time when Aaron was implementing the inversion of the 3rd
> order time to distance relation. In fact up till late 2002 when WC
> started to give good signals, MC was the main way to debug the
> reconstruction.
>
>> +Compare reconstructed unradiated-MC with reconstructed
>> radiated-MC. Can this be done for the same seed on an
>> MC-event-by-event basis?
>
> there is no need for two MC with same seed or not. the input from
> DGen is logged in the ntuples under the names [tpfzq]m[lr].
> flr->Draw("pwl-pml","...")
> gives the deviation of recon'ed momentum from the "true" value. The
> energy loss of deuteron is calibrated this way.
>
>> +The obtained parameterizations of dp,dtheta,dz(theta,p,ID) can be
>> applied event-by-event to the analysis reconstruction.
>
> Is there a point to do this for e+-, pi+- whose energy loss is so
> small? if you do it, you ll find youself parametrizing 0 anyway.
>
> Also, in a discussoin with Nick, we came to the realization that, if
> the analysis is done by comparing "reconstructed monte carlo data",
> then no energy loss correction should be applied to true data because
> the effect is already simulated in the Monte Carlo. if we look at the
> analyiss channel by channel, we can find:
>
> 1. edel: e-loss only affect event selection NOT ANYWHERE ELSE, and
> can be readily corrected.
>
> 2. epel: no comments, leave it to experts, but do not think MC or
> eloss play an important role.
>
> 3. e'p: e-loss needs to be corrected before comparison to MC because
> the white MC method skips reconstruction. but the e-loss correction
> is masked by tracking systematic error anyway.
>
> 4. e'n: neutron is included in this discussion anyway, electrons are
> not affected by e-loss anyways. it does use white MC.
>
> 5. e' inclusive, compare data with MC with e-loss folded in. do not
> correct data. electron e-loss negligible anyway.
>
> 6. e'pi: both particles have negligible e-loss, MC has e-loss too, no
> need to correct data.
>
> 7. e' from proton: same as 5.
>
> When one calibrate for the kinematic correction, it also must be
> recognized that some MC already have e-loss simulated and care be
> taken that it is not double corrected.
>
> Chi
>
>
>
>
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:32 EST