sPHENIX HCal discussion

[Edward Kistenev <kistenev AT bnl.gov>]

John, 
rotating just something does not make much interest - it can’t emulate 
anything even close to triggering capabilities of calorimeter (not counting 
attenuation properties of calorimeter which depend on tower location). The 
real problem is not just measuring tile response with level attached - 
cos(theta) is good enough to describe what’s happening when you tilt the 
tile. The problem is unavoidable selectivity of self triggering, problem is 
in finding the algorithm for unbiased cosmic trigger. It is interesting but I 
am almost certain that both - jet triggering and cosmic triggering are one 
and the same algorithmically, both use regions of interest and thresholding 
to select number of hits in the region and total energy in the region. It’s 
predominance of zenith compared to collision point and spectra modifications 
by modules above what makes the difference.  

If of interest - I already tried to do what you are proposing in simulation 
(rather in emulation) - collected a lot of data from prototype in one 
position and then tried to use that set of data and reconstructed 
trajectories in calorimeter to emulate triggered response to tracks passing 
it at different angles (software still exist and alive) - unfortunately I got 
what expected -  could bias the calibration in any way and direction. 

Using CAEN electronics (if Chi  really can’t introduce majority coincidence 
in selected range of addresses and cut on total amplitude in the same range) 
may help  but … current algorithm in CAEN is not a majority coincidence, it 
is a full coincidence between selected channels. If GSU may further upgrade 
it to majority coincidence - this will be a solution (plus couple of big reds 
on both sides of prototype and safety clearance or moving everything to yours 
or mine garage). But HBD electronics is still alive and well and works. 
Caveat - I never had muon pictures from HBD logic on calorimeter itself as 
good as from CAEN tile testing - let’s see how to connect prototype to CAEN - 
may even reveal something. 

                        Edward

On Jun 13, 2017, at 5:38 PM, John Haggerty <haggerty AT bnl.gov> wrote:

Edward,

We should discuss this in the HCAL meeting, I agree.

But a couple of points people made to me:

- Megan points out that we could spin around a group of tiles without the 
steel more easily than the HCAL prototype.  You might want to do that with 
the CAEN 5702, even.

- I would point out that we need some simulation to compare to in any case; 
it's not so complicated, but we need to account for the angular distribution 
of cosmics.

- Richie points out that you can buy an IHCAL spinner at Home Depot:

> http://www.homedepot.com/p/Big-Red-1-250-lb-Engine-Stand-T25671/100595181


On 6/12/17 12:23 PM, Edward Kistenev wrote:
> Hi, John,
> I talked to Richie in the corridor, he claims that design of the  table 
> which allows rotating HInner for 360 deg’s is made by Chris and is ready to 
> go to the shop this week. If I missed it - still great but if it was never 
> discussed in the group - why don’t we do it this week in the HCal meeting.
>                       Edward
> On Jun 12, 2017, at 11:09 AM, Edouard Kistenev <kistenev AT bnl.gov> wrote:
> John, this is great but the novelty of this setup is limited to new 
> electronics not to calorimeter itself.
> For two years I am wandering around begging to design and build a very 
> simple support stand which will allow for rotating the prototype around 
> horizontal axis (estimates converge around 2 months time to design/order 
> and assemble) - at some time it almost started but … no enthusiasm from 
> project management was always able to kill the idea. Maybe the move to HCal 
> lab will help to revive it - it is something really important. At this 
> moment we have little or no idea of how the calibration will change when 
> towers are repositioned to their final destination and will calorimeter 
> modules in some peculiar orientation (vertical axis) be able to produce 
> enough of measurable signals for triggering or trigger must be correlated 
> between Outer/Inner and emcal.
>                       Edward
>> On Jun 12, 2017, at 9:14 AM, John Haggerty <haggerty AT bnl.gov> wrote:
>> 
>> Anthony and I set up the Inner HCAL (which is now in the HCAL lab) to take 
>> cosmics on Friday and we took a few runs over the weekend.
>> 
>> Some other notes and remarks:
>> 
>> - Taking cosmic data pointed out to me that I didn't stretch the trigger 
>> input to the GTM when I set it up, and since the trigger input is 
>> re-clocked to the 10 MHz clock in the GTM, it misses trigger inputs in 
>> where there is no overlap between the input and the clock; the effect of 
>> that is that the triggers are still random, but you don't get as many as 
>> you could.  I stretched the signal so it's 120 ns long.
>> 
>> - We were running out of room in
>> /sphenix/data/data01/caladc
>> at RCF where we stash the data, so Chris gave us space in
>> /sphenix/data/data03/phnxreco/
>> and I moved all the stuff that used to be on data01 to there.  Probably I 
>> could just delete it, but I thought we'd keep it around for a while.
>> 
>> - There are two files of cosmics (about 3500 events) in
>> 
>>> /sphenix/data/data01/caladc/hcallab
>> 
>> with 14 bit goodness; we tried to keep the channel ordering the same as 
>> before (64-95), but the high and low gain channels are switched around 
>> (for the afficionados, we needed to reverse the polarity of the signal 
>> relative to what we had in the HBD electronics, so we flipped the slice on 
>> the preamps, which switches even and odd).  The good stuff is here:
>> 
>>> cosmic_2017_06_09_17_14.prdf
>>> cosmic_2017_06_11_16_32.prdf
>> 
>> triggered by paddles under "column 0" of the Inner HCAL.
>> 
>> -- 
>> John Haggerty
>> email: haggerty AT bnl.gov
>> cell: 631 741 3358
>> _______________________________________________
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-- 
John Haggerty
email: haggerty AT bnl.gov
cell: 631 741 3358
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