physics with the hft prototype?

Physics with the HFT prototype?

J. Bouchet for the HFT-soft group

04/21/23 Star Coll. Meeting, LBNL, Nov. 2011 1

1. Motivation2. Results of simulation :

a) Acceptance optimization studies

b) Tracking efficiency studies with TPC+PXL

3. Next steps

Motivation• PIXEL detector is the inner sub-system of the HFT tracker

in STAR• 3 (or 2 or 4) PXL sectors (out of 10) will be installed in

STAR next year for Run-13 as an engineering run • Question : Which geometry is the most efficient for track

pointing and physics measurement ?


• for low Pt D0, opening angle between daughters is large.• For higher Pt D0, the openingangle decreases.Different Pt D0 regimes lead todifferent configurations of the sectors.cosine(φpion-φkaon) vs. PtD0


=0

=36

=72=108

=180

=252 =288

=324=216

=144

2 configurations studied

Triangle-shape Joined-shape

1 sector covers 36


Simulation Setup1. Input:

– Generate 100k D0 with flat Pt in [0,5], ||<3,|Vz|<10 cm– Count :

• NN : # of D0 input

• N0 : # of D0 after Pt cut for both daughters and|| <1

• N1 : # of D0 with above cuts + TPC>10,PXL=2

• N2 : # of D0 in triangle configuration

• N3 : # of D0 in joined configuration

• Single track efficiency/ghosting• Modify the existing geometry file with

– Removal of SSD and IST– Localization of 3 pxl sectors according the patches configuration

• ~500 central AuAu Hijing events but NO PILEUP– Plus minbias AuAu hijing events for creating pile-up


Cuts on Daughters:||<1, TPC>10,PIXL=2,

triangle(N2)


Cuts on Daughters:||<1, TPC>10,PIXL=2,

triangle(N3)

• Can we do anything substantial here ?• Any physics with the prototype?

What physics can be achieved ?

Charm cross-section Charm Rcp04/21/23 7Star Coll. Meeting, LBNL, Nov. 2011

TPC+PXL Efficiency/ghosting studies• BFC chain reconstruction and tracking (Sti) with only pixel

prototypes geometry = no material form SSD nor IST.• 350 hijing events, no pile up.• Vertex cuts :

– |Vreco -VMC| < 0.01 cm : good reconstruction vertex– |Vreco | < 10 cm

• Tracks cuts :– Reco TPC hits >15– |η|<1

• The definition is :– effSiGoodRc = # of tracks with 2 good pixels hit / # of tracks with 2 MC

pixel hits– Ghosting = # of tracks with 2 good pixels hits / # of tracks with 2

pixel hits

04/21/23 8Star Coll. Meeting, LBNL, Nov. 2011

TPC+PXL TPC+SSD+IST+PXL

Hijing – NO Pile-up

Good tracking efficiency (but no pile-up yet)

Efficiency with TPC+PXL prototype


Ghosting with TPC+PXL prototypehttp://www.star.bnl.gov/protected/jetcorr/kapitan/HFT/upgr15_2010/productionQA/thin/CD1/single/

Hijing – NO Pile-up

TPC+PXL TPC+SSD+IST+PXL

Low Ghosting


Next steps• Include pile-up events :

– Will increase single track ghosting

• Study reconstruction of D0 in this environment– So far it looks encouraging– We have two configurations for x-section and Rcp

measurements (if everything else goes well)– Please think of what physics YOU would like to do.

We will help you run the simulation.



Back-up

SSD+PXL

04/21/23 Star Coll. Meeting, LBNL, Nov. 2011

Note : the x-axis scale changes with the layer

Pixel outer layer Pixel inner layerSSD layer

13

PXL only

04/21/23 Star Coll. Meeting, LBNL, Nov. 2011

Note : the x-axis scale changes with the layer

Pixel outer layer Pixel inner layerSSD layer

14

comments• With SSD :

– Residuals in r/phi for the outer pixel layer is better than w/o SSD

– Residuals in r/phi for the inner pixel are slightly better than w/o SSD

– Residuals in r/phi and Z are asymetric (due to the asymetric resolution of SSD) for both outer and inner layer

• w/o SSD:– Residuals in r/phi and Z are symmetric (due to

the same resolution of the pixel)



Some precautions to make

1. Optimization wrt TPC sectors :

•TPC has 12 sectors

•PIXEL has 10 sectors

2. TPC sectors health during a physics run : we want to avoid to place a PXL sector matching a unhealthy TPC sector


MRPC ToF MRPC ToF barrelbarrel

100% ready for run 100% ready for run 10 (now!)10 (now!)BBC

PMD

FPD

FMS

EMC barrel EMC End

Cap

DAQ100DAQ10000

FGT

Completed

Ongoing

MTD

R&DHFT

TPC

FHC

HLT

physics with the hft prototype?

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