Tell us about it's very taxing and very taxing performance in round two.
And so please go ahead matcha
Good afternoon to everybody. It's a big honor for me to be here and give this
presentation on behalf of Dallas collaboration about the texting detectors
and the texting performance in Ubuntu with Ellis. During the presentation, I will
talk about the Alice experiment and in particular, I will talk about the early D
IDs detector in one year from today, I will describe the event reconstruction and
the taxing technique for the reconstruction in particular of every
flavor vertices. Then I will talk about some interesting physics results. The
TELUS was able to provide thanks to its vertex in capabilities. And finally, I
will spend few words about the IDS upgrade. Elisa is general first experiment
composed of a central model with up to durability coverage between minus 0.9 0.9
and immune spectrometers for up to 80. I don't have the time to describe all the 19
subsystems of Alice, I will just spot the free of the detectors in the central
bottle involved in the dirt fixing and in the tracking. The inner muscle detector of
the central model is the inner tracking system, which apart from the localization
of the primary vertex as his primary goal, the localization of secondary vertices
have a flavor as well in the case. And in addition, the inner tracking system is
involved in tracking helping the time projection chamber on this duty. The temp
projection chamber is the main tracker of their Lisa and also identifies charged
particles via the measurement of ionization or unionization energy loss.
Furthermore, an additional detector involved in this trucking duties is that
your team which also helps in the electron identification we have the measurement of
transitional radiation. As I said the innermost detector of the central barrel
is the inner tracking system, which is a fully silicon detector composed of six
cylindrical layers, the silicon pixel silicon raised and silicon strip detector.
This is a negreanu Laurie apparatus able to cope with thousands of trucks per unit
of rapidity that we have in high volume collisions, and it's also able to detect
simultaneously more than 10,000 trucks. As I anticipated the main duty of these
detectors is the reconstruction of secondary vertices of every flavor abs in
the Kazem in a separated way from the primary vertex. In addition, this detector
helps improve with the tracking and also tracks as low particles that are not able
to reach the TPC and be tracked their events recorded by Lisa, reconstructed
according to a predefined reconstruction flow which starts with appealing Not a
reconstruction of the interaction point by exploiting the DSP. In the meanwhile, the
tracking in the DPC starts starting from the outer edges of the detector. And as
soon as the tracks are reconstructing the EPC, they are belong to the IDs. And this
prolongation is done with a matching efficiency quite high of order of 85 90%
almost flat in terms of momentum and while we produce those in our Monte Carlo
simulations, as soon as the tracking arrives, it it is also there's no
particles can be tracked them by the usage of the IDS stand alone, and then the
prolong tracks are refitted outwards in order to match the more efficient external
detectors. And finally, the trucks the global trucks are subject to a final
inward defeat them that is very useful for the improvement of the trucking
performance as you can appreciate from the left block, as soon as we require the
prolongation of the tracks to the ITA from TPC to IPS. we improve by a factor of two
or three, the resolution in the curvature of the track and as soon as this set of
global tracks is ready, we can do the final introduction vertex finding and then
characterize completely the event. At this point we can look for physics and in
particular, reconstruct secondary vertices of bofur. Weekly case, for example, their
partner item and the case associated to every flavor such as the measurements
along to see, candidates associated to these secondary vertices are then counted
through these environments distributions which are available after the
reconstruction of secondary vertices. This reconstruction is done by fully
reconstructing the final Atlantic state. And the vector x position is found by
minimizing the distance among the Delta trucks. The reconstruction of secondary
vertices takes place by approximating tracks close to primary vertex a straight
line. But despite his geometrical
approximation. Even in the worst scenario, however, we have really negligible bias in
the position of the vertex and this simplifies all the procedure. The
reconstruction of secondary vertices is also very important in order to be able to
exploit that at analysis level. Some interesting variables such as decay length
and pointing angle which are strictly related to the topology of the decay. The
secondary vertices reconstruction is also performed the MonteCarlo simulations after
correcting the reconstructed tracks in a data driven way, for the For what concerns
the input parameter is a parameter to Primary Ethics. And with this procedure,
we report to the resolution of the primary value of the input parameter sorry, of
trucks in MonteCarlo to match the one in data. This procedure is very important to
not only for efficiency corrections, but also to provide unbiased templates for
input parameter based analysis. After this short introduction, I wanted to speak
about some interesting physics results from Alice in proton proton and lead light
collisions. And to start with this, I show you a typical lead collision. The teleSUR
g study in 2018 taking campaign as you can appreciate from these block them, the
truck density in the central model in lead collision is very high. We are talking
about several thousands of trucks in central events. And as you can understand
that this makes the analysis in every flavor of every flavor more challenging in
his environment, due to the huge combinatorial background that we have to
cope with. But in any case, there are construction of every flavor of secondary
vertices is fundamental for Alice for the study of the courtroom plasma that is
produced experimentally via the API and collisions. As a matter of fact, the
chairman beauty quarks are produced before they could use information. And for this
reason, they can be considered effectively unique probes of PGP since they experience
the full evolution of the medium thanks to the protection capabilities of Alice today
I'm able to show you this very nice plot. This compilation plot of the Chung flavor
family, where you can appreciate the nuclear modification factor array for
different channels of drums. This variable they are a is very important in heavy ion
collisions, because it provides a natural comparison between the behavior that we
observe in the ion collisions and they wanted to serve in in proton proton
collisions. And this variable is observable is sensitive to several effects
such as the medium button energy loss, the urbanization mechanisms that involve every
quirks and effects related to thermalization and especially fusion
coefficients through PT. Elisa is able to measure electric And disentangle the
beauty component of these electrons from other sources in both proton proton and
lead collisions. And these is possible because beauty algorithms have longer life
time. So, then charge models for example, and as a consequence they decay products
and in particular in this case the electrons have a larger distance to close
this approach with respect to primary vertex and this topological property can
be exploited when looking at data in the topology, you can appreciate the input
parameter distribution which is described with the MonteCarlo template speeds of
different sources. In particular the red template that is the one of electron from
UT Adams. He has larger tastes with respect to the green one, which refers to
electron from charm. And these reflects exactly the topology of dedicated there
was explaining before. Thanks to this, we can then provide interesting measurements
of beauty electrons Such as the elliptic elliptic flow of electrons in semi central
led collisions. As you can see here, this is a very recent result of Edison and the
such measurements are really important for us to have a further insight of the
physics of beauty in the plasma battalions can do even more and the reconstructor
secondary vertices of charma are drones associated to beauty Ks. And on the left
you can appreciate a compilation plot of production cross section of DME prompted
the measures in proton proton collisions by TV and on the writer the comparison of
nuclear modification factor of both prompt and on prompt digital mesons. All these
measurements are possible by exploiting different decay topologies which are
resolved in alias thanks to the vaccine capabilities, which are then pushed up by
the usage of machine learning tools, which make the separation among prom D known
from D Background components possible.
Looking at the results, we can appreciate on the right plot an inter of largest
suppression for prompted the zeros with respect to non compliance at intermediate
PT and these measurements are really important for us because comparing them
with theory we can really assess the acute GP properties. battalion is a competitive
experimental seen proton proton collisions, for example, it's the only
lithium experiment able to measure lung the C volume down to one g v over c. EDT
and the low PT region. region is very important for this because here is where
we spoke to the largest difference between the measurement and the urbanization
models. And in particular, the charma. baronova measuring ratio that we measure
shows significantly higher values, then expectations from Monte Carlo simulations
that are tuned to reproduce the plus or minus measurements and these recent
measurements from Elissa interesting because challenge modernisation models and
here the physics seems to hide something really interesting. Another measurement
provided by a less important proton collision rapidity is the production of
Crompton on project site, which is reconstructed in a central Barela. Between
in the in the decay channel a plus c minus. The non prompt component is
distinguished from the prompt one by exploiting the sizable beauty decay other
and decay length.
And the thanks to this
LS is able to provide the measurement of the non projects a fraction of meter PDT
down to one GB oversee and this is the lowest value of terms of momentum explore
the four DS measurement. In addition, the measurement of Le sent me the rapidity of
content on from chip side are complimentary in terms of rapidity
coverage, to the LSE v one, and this can be nicely appreciated on the right block,
where you can see a very nice measurement of PCB at four feet in blue. completed by
the Black Point from Alice. But then Alice is able also to reconstruct secondary
vertices associated with the case. And one of great interest for at least in the last
in the last year or so, is the one of the hyper Triton became a new friend via the
measurement of the lifetime of helium three is very important to solve to try to
solve the so called icon puzzle which has huge interest in astrophysics because it
concerns the discrepancy between the expected values of neutrons or masses
which is lower than the absurd one for some cases,
and that the three minutes again that
these accesses the muscle is justified according to model. So, by adding an
additional repulsive contribution, we should which should come from either a
nuclear nuclear interactions and they protect on lifetime is an experimental
problem of this potential. So, this is really interesting question Decent. The
eye protection candidates are reconstructed in a central bottle with a
visitor finder technique. And the signature of Viper Triton is
reconstructing a different CT interval so that the measurement of the lifetime is
possible by fixing this distribution. As you can appreciate the from the
compilation plot on the top. On the bottom left, you can see that the contribution of
Alice in this field is really outstanding. And in particular, the precision in the
measurements for malice improved in the last year thanks to the new lead the lead
to data samples at fight TV recorded in 2018 and 2015 data taking campaigns.
Before concluding my talk, I want to spend a few words about the IDS upgrade and I
take the chance to invite you to follow their alley subgrade talk in which you can
know something more about a new vertex detector that will be available in LS
after the long shutdown tool Which is the newest form of tracker the IPS will have a
renewed layout and is ready to be installed after the long shutdown too. And
in particular, the IPS will have an additional layer closer to the
introduction point. And in particular, it will be the first large scale occupied
monolithic active pixel sensors detector and this will let us improve the
performance in the reconstruction of the flavor vertices and reduce the
uncertainties at low PT in the performance of this detector will improve not only
because it will be closer to the interaction point, but also because it
will be lighter in term of a material object with a reduced and multiple
scattering property as a consequence, then it will be faster in terms of readout and
we Yes, we are talking about a factor 100 have improved the readout rate and then We
will have an improved spatial resolution thanks to an improvement. And thanks to
this and also thanks to the further upgrade. So that we we will have in the
ATLAS detector, the performance of the full apparatus will improve. And for this
reason, we are really looking forward to the last long shutdown and long shutdown
free data taking campaigns. But in any case, we can say that Ellis has been
already obtaining remarkable results in undoing all the collision systems
considered. Here I report a non exhaustive list of very interesting talks from Alice,
about physics perspectives, I lights and upgrades. I invite all of you to follow
them and also the other really interesting talks from Alice. And in general, I wish
you very nice
conference.
Thank you very much for your attention.
slot machines and questions, please raise your hand
don't see anything immediately.
It is what it is ask them what they don't see the right hand.
I have for four speakers you can't raise your hand but you can unmute yourself
anyways.
If you have a question yeah okay, so yeah, I mean, cuz I mean your parameter solution
is shown on page nine.
Okay, you didn't fully understood to what was your module.
So what we do before constructing secondary vertices of every flavor out on
the case in MonteCarlo, is to apply a data driven correction track by track on the on
our reconstructed tracks in MonteCarlo according to what we see in data And this
data driven correction is useful to make that a solution in MonteCarlo that is the
green one originally to match the one in data. So, the effect of the correction is
you can see, looking at the red points, which perfectly match the ones in data
goes from one to kind of I mean for data to you, I mean, this is the solution, do
you compute the primary solution?
we propagate the tracks towards the primary vertex and, and we measure the
impact parameter of prolong tracks in the IPS and here the IPS plays a crucial role
to these
because we just forward for MonteCarlo today.
Yeah, yeah. So, just a Monte Carlo correction, reconstruct the trucks before
reconstructing the vertices.
Okay, thanks.
Okay, thanks. I'm for one.
One more quick question. No one else has one I have kind of a related one on slide
13 we should have a nice separation between beauty and charm and prompt
events. And so, I don't have a feel for pileup at Alice, do you have any issues
with PV Association, associating tracks to the wrong PV.
And yes, sir, we have about we are able to remove a pileup sir by looking also at
correlation among different among signals from different detectors. And so, we
discover through these correlations we are able to also treated these pile up
component. So yeah.
Okay, very nice. There we do do something similar for separating beauty and charm
and lgtb this getting the wrong PV is sometimes an issue