# Presentation: 076281

## STAR Calorimetry

**STAR Calorimetry**

-  **Status/what is it?**
** ****Performance &             ****	****physics**
** ****Operations/anecdotes**

- W. W. Jacobs for the STAR Collaboration IUCF and Dept of Physics, Indiana Univ.

**XIII Int’l Conf. on Calorimetry in High Energy Physics, 26-30 May 2008, Pavia Italy **

## STAR Calorimetry: meet the players

- physics connections

- The STAR detector

***STAR Calorimetry: meet the players***

- Forward Meson Spectrometer (FMS)

- Endcap EMC Calorimeter (EEMC)

- Summary

- Barrel EMC Calorimeter (BEMC)

- other calo‘s ZDC, FPD++

- Introduction

## STAR Calorimetry Coverage & Brief Timeline

***FMS, EEMC and BEMC provides nearly complete EM coverage from -1 ************ ******η****** ************ +4***

***STAR Calorimetry Coverage & Brief Timeline***

**Notes:**
Towers: 4800 BEMC + 720 EEMC + 1264 FMS (Pb glass) + 150 FPD (Pb glass) = 6912 

## STAR Calorimetry Introduction Summary

_**Overall EMC Modus Operandi and Comments**_:
-  **incremental install, commission, calibrate, upgrade and maintain** (e.g., the STAR calorimeters were not among the “baseline” detectors)
-  many of same people involved & relatively small group
-  need for increased capability/physics output each run period (few examples):

- 2002 pp: fwd single spin asym and xsec (FPD proto)
- 2003 dAu: x-sec (1/2 BEMC)
- 2003-4 polarized pp: G inclusive jet results (1/2 BEMC)
- 2004 AuAu: heavy flavor x-sec (~1/2 BEMC)
- 2006 polarized pp: di-jet Sivers w/ EMC trig data (full EEMC/BEMC)
- Recent: BEMC pp x-sec & BEMC and EEMC ALL as well as
- neutral(EMC)-charge particle correlations ...

- EMC’s dominate triggering for polarization physics as well as in recent years for heavy ion data bandwidth; EMC data now also becoming major part of STAR physics analysis & output (recall STAR baseline detector & “heart” is TPC)
-  overall things have gone well and the EMC performance/operations, driven by $ and/vs. physics has worked (maybe not perfectly but) well -> great productivity!

## STAR EMC Subsystem Support

_**EMC common Equipment, Analysis and Calorimeter Support Procedures I:**_

**STAR EMC Subsystem Support**

-  Barrel (BEMC) & Endcap (EEMC): both sampling calorimeters, similar overall structure/features but differing implementation (some significant), so we have =>
-  _**STAR EMC “operations & detector analysis” based group (EMC^2)**_
-        -> weekly phone meetings (and some collaboration meetings)
-  detector ***equipment support*** and detector perfomance issues
-  ***calibrations***, run status tables/data base (for replay) of detector components
-  detector based ***analysis alogorithm*** development (from physics work groups)
-  ***software*** ... including EMC subsystems coordinators reporting to STAR soft

-  Tower FEE digitizer: common BEMC & EEMC hardware (example):
-  32-input 9U digitizer w/ 12bit ADC/chn, 10 MHz crossing & pipeline architecture; (for EEMC remove “magnetic” noise suppress/run at higher PMT gain on poletip); trigger section outputs high tower (HT) and trigger patch (TP) information
-  early runs and subsequent: “ghost peds”, n*256 noise, header corruption traced to clock issues ... prob jumped from EEMC to BEMC and back => _now diagnostics_
-  EEMC required remoted pwr supplies (due to poletip fields) => eventual real solution to serious BEMC supply fail; subsequently separate more crate func’s

## STAR Full Barrel EMC: Component Overview 

***STAR Full Barrel EMC: Component Overview ***

- -1.0 < η < 1.0; full azimuthal coverage
- 4800 towers; 36k SMD strips; 4800 presh
- 120 modules (40 towers/module)
- (Δη, Δφ)module~ (1.0, 0.1); Depth = 21 Xo
- (Δη, Δφ)tower~(0.05, 0.05)
- dE/E ~ 14%/√E
- Shower Max Detector (SMD) @ depth 5 Xo
- (Δη, Δφ) ~(0.007, 0.007)
- Pre-shower detector (PSD) @ depth 2 Xo
- First 2 scintillator layers combined/tower

- R ~ 2.3 m

- EMC Module

- mod- ule end view

- dbl-sided design gaseous

## Summary of some BEMC Components Performance Level  

***Barrel EMC Status, Perfomance & Operations I***

-  **Pwr supplies, crates, etc.**
- Original tower FEE crate design: compact ass’bly including integrated pwr supply, controls/LV for CW bases
-  **many**  supply failures (~ 1/wk when running) -> likely due to mag field; **remote supplies => solution!**
-  coupling of CW LV to FEE power  (reduced flexibililty and slam CW w/ FEE cycle) => **separate supply**
** **similarly, coupling of base HV control function through FEE crate =problems! => **separate controls**

## Barrel EMC Online & Offline Calibrations Part I

-  LED system to adjust indiv HV (or e.g., 28 to 60 GeV full scale to match EEMC for run 5)
-  Slope equalization used at beginning of run to fine-tune HV (is fast and relative in  ring)
-  During run start, check gains using MIPs; data production requested in fastOffline

-  Full calibration uses muDSTs (offline)
-  MIPs set relative gains for each tower;  electron E/p used to normalize -rings
-  beginning in 2006, sufficient stats for tower-by-tower electron E/p measurements
-  revisiting higher pT electron and  calibr

_***Pre-run and online***_

_***Analysis and offline***_

- MIP gains (uncorr’ed)

- Electron full-scale calibr

- Full scale projection

- [Systematic artifact of large rings -> particle isolation issues => correct to flat response]

## STAR Endcap EMC: Component Overview

***STAR Endcap EMC: Component Overview***

- 2 half annuli – 1 < h < 2; SS structure
- 23 layers Pb/SS laminate; Depth = 21 Xo
_**720 projective towers**_ (comprising 24 layers)
- 6° and 12° megatile; ~ 100% coverage
- (Δη, Δφ)tower~(0.057 to 0.099, 0.01)
- dE/E ~ 16%/√E
**Depth segmentation**
_***2***_ separate _**preshower**_ (1,2) layers (1440 chns)
- high position resolution _**SMD**_ @ ~ 5 Xo
-     -- 6912 triangular-shaped scint strips
-     -- (Δη, Δφ) ~(0.003, 0.003)
_**postshower**_ 24th layer (720 chns)

- SMD, Pre/Post: MAPMT readout

- 4 FEE w/ 4 chns x 12 bit ADC/ea

- CW base

- MAPMT

- SMD

- Towers

- 12 ass’bls = 192 chns/box

-  check!

## STAR Endcap Perfomance & Operations

| Maint. period | tubes [720] | Bases [720] | FEE digit [24] | Tubes [576]  | bases [576]  | FEE cards [2304] | IFB cards [576] |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Fall-05 | 0 | 1 | 1? | 0 | 12 | 16 | 2 |
| Fall-06 | 2 | 6 |  | 0 | 8 | 8 | 1 |
| Fall-07 | 0 | 6 |  | 1 | 6 | 6 | 1 |
| Fall-08 | (3-4?) |  | 1 | (1-2?) |  | (3?) |  |

| Towers | MAPMT |
| --- | --- |

- .

-  2 prob HV controllers (3 tot)
-  _chiller bubbles & compressor fail/shutdown problems_
-  ~5% boxes require de-fibering for maintenance work

- _EEMC Config/repair issues_:
-  all PMT and FEE on back of west poletip (54 fibers to data collectors)
-  ~ 1kG fields require PMT’s in shielding (boxes); MAPMT/FEE compact ass’bly
-  access to poletip requires manlift, & if  running, STAR magnet rampdown/lockout -> minimum few hour turn around
-  rely largely on scheduled/bi-weekly ~ 1 shift access for repairs/maint during runs
-  shutdowns -> access limited w/ poletip retracted for work TPC, TOF, BSMD, etc
-  hence, require ~ 2-3 weeks w/ poletip attached (single box repair turnaround ~ 1 day) ... includes “piggyback” of box to neighbor box leaving light fibers attached
-  **Good news: EEMC failure rates are relatively low & declining!**

- _Offline QA w/ peds:_

-  ped monitoring catches many probs: complete comp fail, fat ped diagnostic, stuck bits, data base swap, etc. etc.
-  BUT, recent example of low chns stuck 50% -> eluded all diag!

## ENDCAP Offline Calibrations Part I

***ENDCAP Offline Calibrations Part I***

- use SMD isolation pattern each plane (26-fold condition):

_**only partial tracking -> “invent” MIP ID w/ SMD+isolation+other det components **_

- SMD u(v) cross section view

- 0000000 -- X[X] -- 0000000

-          ideal 4096 @ 60 GeV ET; RMS ~ 9%
-   run 5 to 6 (example): gains stable < 1%, so no indication of fiber, scintillator or PMT degradation!

## Performance Issues & (E)SMD for  Separation

-  ****-jet spin meas in pp (qg Compton scatt) of interest re: gluon contrib to proton spin
-   Endcap component design: tower, **triangle-shaped scint SMD**, & pre1,pre2, post

- initial simulations => expect/need ~ x 3 reduction of ’s at pT ~ 10 GeV/c (more required to go down in pT)
-  SMD shower shape discr analysis (e.g., max sided fit residual in u and v planes) => detailed response studies
-   simulations not realistic => try photons from “” decay to replace MC shower shape (vs. sector, “”,φ, E ...)

- Event from di-jet analysis w/ pre1= pre2=0 & enhanced **** signal

- First look at discr w/ “data driven” pythia for bkgrd & signal slices

_**-> Extensive analysis ongoing  w/ run 6 data**_

## STAR EMC Calorimetry Operations & Procedures

**Common EMC support II:**

-  “summer “ maintenance: collider not running –> weather, electricity costs
-  priorities: repair, upgrade, etc.
-   run startup: timing, peds (triggering), pulsers,  etc. (EMC expert)
-  w/ beam minbias -> QA response; calibr -> then trigs HT, JP, L2 and tune (expert)
-  running mode
- Monitoring
-  online QA-plots (fraction of events/all triggers) ... saved per run (crew&expert)
-  L2 trigger diagnostics & monitoring plots, ratios available  ~ minutes (~expert)
-  Problems
-  crew: reset supplies, reload FPGA (radiation upsets, etc.)
-  experts: mask hot channels, stuck trigger bits, all other probs
-  Special runs
-  minbias/fill for status tables; background (HT, JP w/o minbias); other special
-  Access
-  ~ bi-weekly (1 shift); on demand under fill prep/machine probs/emerg (.25-1hr)

## Level 0 High Tower & Jet Triggering in STAR

- 2006 rate ~ 2.5 Hz, sent to  tape without prescaling

***Level 0 High Tower & Jet Triggering in STAR***

- 2006 rate ~ 150 Hz, use L2 trigger to fit limited bandwidth

***Trigger either on***
***HT******: ************ 1 (of 4800 BEMC or 720 EEMC) tower E******T****** > thresh - ******Or***
***JP******: ************ 1*** ***(of 12 BEMC or 6 EEMC) hard-wired jet patch  ********* *****E******T****** > thresh.***
***[note: also a minbias cond]***

**BARREL EMC**

**ENDCAP  EMC**

- 12 bit adc  -> 10 bit at FPGA ->   _**then**_                                         subtract a “ped_4”  (put in range 16-31 chns)

- drop 2 lsb’s and Σ 8bits= Trig Patches ~ w/o noise

**Tower digitizer trigger section**

- trig patch: 6 bit HT

-  low thres HT (HI phys) -> hot towers
-  JP (spin phys) -> peds, stuck trig bits

**Issues:**

- Run 9 “DAQ1000” will relax these limits – but data volume an issue!

-  plan L0 wiring/FPGA upgrades -> smooth out present trigger response in φ and η.

**Notes:**
Message:
Key for spin : TPC+EMC
Key for rel lum : BBC=minB triggers

## Barrel

-  Samples all events! (STAR “Pplot” just ~1%)
-  Trigger sorted/other diag (“Pplot” random sampling)

**Pedestal**
**residual**
**per tower**

**TP **
**frequency**
**per trigger**

**HT Frequency/trigger**

-  Endcap Towers

**Barrel**

**Endcap**

**Barrel**

**Endcap**

***QA Feedback from L2 Trigger Algos***

**di-jet**
**correlation**

**examples here w/ some problems!**

## Di-jets: (“Sivers” AN measurement) Direct from L2 Trig 

***Di-jets:***** (“Sivers” A****N ****measurement)***** Direct from L2 Trig ***

*** ******L2 di-jet triggering: identify 2 localized clusters, ************ ************ ************ = 0.6 ************ 0.6,*** ***with E******T******EMC****** > 3.5 GeV, |************ | > 60*********
*** ***_***monitor ***_***(these/other ) data and physics online***
-  replay trig data offline (fast) to optimize cuts, etc.

*** *****transverse single spin asymmetry results**: (2006 p+p, 1.1 pb1; 2.6M di-jet trig’ed events)
-  both quark & glue Sivers funcs smaller than initially expected for pp->dijet+X [PRL** 99, 142003** (2007)]

## What is FMS? (Forward Meson Spectrometer)

- 3.8 cm square x 60.2 cm
- π0 vs. γ to 60 GeV
- Large cells / 788 total:
- 5.8 cm square x 45 cm (Scott F2)
- π0 vs. γ to 40 GeV

***What is FMS? (Forward Meson Spectrometer)***

-  new 2-m square, 1264 cell Pb-glass array at 7.5 m from center of STAR
-  “stacked for physics” in forward direction

-  mixture of recycled/built parts (“green”det!);

-     Pb-glass from E831/FNAL (large) and IHEP + JLAB (small);  bases & tubes, FEU/resistive and XP2972/C-Walton, respectively, latter from JLAB + Yale AGS-E864 + some built
-     all dets re-wrapped and QA/tested

-  north-south split at beam pipe and movable by carriage; fwd position => strong xF and pT correlation
-  an advanced custom readout for FMS cells was built (see next)

## FMS Readout and Triggering

-  DAQ linux based: stand alone or w/ STAR DAQ (or both)
-  trigger FPGA info shipped on fiber to PCI receiver (see next slide)

- Readout of 1264 channels of FMS provided by “QT” boards.  Each board has:
-  32 analog inputs (w/ active ~ 80 ns capture time)
-  12-bit ADC / channel (dual integ front end/switch)
-  5-bit TDC / channel (5 ns time stamp bkg reduction)
-  five FPGA for data and trigger
-  operates at 10 MHz and higher harmonics
-  produces 32 bits for each RHIC crossing for trigger

_**Schematic of 1⁄2 of FMS readout:**_

## FMS Initial Run 8 Performance & Operations

- Using adapted shower shape codes from PFD, and preliminary calibr/efficiency: clear evidence for o events in large and small tiles -> and performance only expected to improve

** ****detector capabilites commissioned as needed for dAu, then polarized pp running**
** ****LED gain tracking system instituted **
**  ****at end, < ~ 10 “problem channels” overall**

_**FMS Triggering:**_
-   treats groups of 16 crystals
-  High tower trigger (implemented) – select highest of 16 ADC values
-  “Overlapping patches”: select contiguous group of 6 bits sum and 6 bits HT; dynamic clustering effectively a movable trigger patch (to be commissioned)

## Future Developments for STAR Calorimetry 

_**Readout and Triggering improvements: **_

_**Tracking:  **_

_**Shielding, material and etc. **_

-   upgrades to trigger control/driver units -> more EMC thres’ds; continue w/ further devel of (**B/E)EMC L2 and FMS trigger algo’s** for efficient triggering/monitoring
-  parts of EMC readout now slow! re: new “daq1000” STAR readout -> rework barrel **SMD/preshw RDO crate FPGA**; all receivers to **DDL transfer** (ALICE) and PCI/linux

-   fight battle re: **“extra” material** assoc w/ central tracking and other dets upgrades
-   RHIC **tunnel shielding** for remaining EMC “hot spots” -> bandwidth/data integrity

-  **forward GEM tracker** (FGT)  -> STAR upgrade plan for ~2010 (e.g., charge sign separation of W decay e’s for flavor dependent spin PDF determination)
-  optimize (meantime) forward **tracking algo’s** & new DAQ hrdw for max TPC reach

_**Calibrations, algo devel and etc. **_

-   improve **tower calibrations** (e.g., ******0**’s & e’s where possible); address other (B)EMC components; important for next tier of physics output
-   **gamma********0**** and e/h discrm algos** ****jet currently of interest for spin, HI and QCD)

_**Other/diverse **_

-   w/ running “hiatus” -> gather & re-energize troops for all aspects of **EMC support**!

## Summary for STAR Calorimetry

-  STAR Calorimetry was installed and commissioned over several years ->
- the combined Calorimetry now provides nearly complete EM coverage from -1  η  +4, and serves a variety of both heavy ion and spin physics needs
-  At present, all EMC components are running well and increasingly contributing to STAR physics; several examples in triggering and EMC response analysis were presented
-  Selected EMC operations and monitoring procedures, component performance issues and other details were reviewed for this operating set of Calorimeters
-  Next work and EMC related upgrades were listed and discussed; these efforts will enhance the performance and physics output of the EMC/STAR
-  We look forward to many future years of STAR EMC successful operations and physics!

- Note: some early descriptive EMC references are
-  Barrel EMC: Nucl. Instr. Meth. 499, 725 (2003)
-  Endcap EMC:  Nucl. Instr. Meth. 499, 740 (2003)

## BACKUP

- SLIDES

## The STAR detector

**     ****E-M Calorimeter**

**Time of          Flight**

**Projection               Chamber**

- The ***STAR*** detector