More design Works• More simulation to study the physics reaches with BESIII. magnet? solid angle coverage ? Identify several important physics topics, and study

the physics performances.

D physics, leptonic, semileptonic, D-Dbar mixing

What is the luminosity needed after CLEOc,

1 10 to 33 or > 3 10 to 33

Some physics topics demand high mom. Resolution and very good PID

•More study about IR, the backgrounds and mask design.

• More detector simulation to arrive design optimization

- TOF time resolution, the z position error from track extrapolation?

- the low limit of photon detection?

• Each system (detector components, DAQ and electronics) needs R&D, prototypes

• Commissioning machine with detector outside beam line, radiation

issue.

Major issues related with BESIII design

• The radius of crystal calorimeter, affecting performances and cost. Possibility of using CsI crystals as EMC.

Personally, CsI is fine, except radius problem, if we use existing magnet (CLEO I)

• Backgrounds associated with machine operation, the design of interaction regions, vacuum, masks, etc.

Experienced man power big issue

Subsystem BES III CLEOc

Vertex

MDC

XY (m) = 130 90

P/P (0/0) = 0.8 % 0.5%

dE/dx (0/0) = 7 % 6 %

BEMC

E/√E(0/0) = 2.5-3 % 2.0%

z(cm) = 0.3 cm/√E 0.3 cm /√E

TOF T (ps) = 65 ps? RICH

counter 12 layers(?) 3 layers

Magnet 1.2 tesla 1.2 tesla

Competition from CLEOC

Serious challenge from CLEOC project

Design machine and detector to be as advanced as possible,

Complete the BEPCII/BESIII project ASAP

Collaboration between BES and CLEO

-Fit with BEPCII lattice, space? 1.8 m from IP to SCQ

- Schedule, commitment of detector moving?

- Physics collaboration?

BESIII Collaboration

Welcome international collaboration, and domestic collaboration, groups to participate in BESIII project

Design, MC simulation, decision making process for making

Final decision,

Sub-detectors R&D and construction

Electronics R&D and manufacture

Online/Offline software, more flexible arrangement

Software package

Reconstructions and Calibration code

Physics study

In charge of some sub-system or send people to IHEP

•about Cost and schedule

Cost for EMC, SC magnet and electronics is most crucial;

MDC, EMC and SC magnet (including iron structure) on critical path.

•Man power issues

Serious man power shortage exists, especially the experienced people.

Cost estimation of Detector subsystem (Preliminary)

In M RMB (1 USD= 8.3 RMB)

• Beam pipe + vertex chamber 3.0

• MDC 11.0

• TOF 6.0

• Barrel EMC 54.0

• Endcap EMC 20.0

• Barrel Muon detector 4.5

• Endcap Muon detector 2.5

• Super conducting magnet 45.0?

• Luminosity 2.0

• Electronics 63.0?

• Trigger and DAQ 13.0

• Total 224.0

about 1/4 to 1/3 of the detector budget either be contributed other sources

or be staged.

Schedule

• Feasibility Study Report of BEPC II has been submitted to the funding agency .

• Technical Design Report of BEPC II to be submitted by first half of 2002.

• Construction started from Summer of 2002

• BESII detector moved away Summer of 2004, and the BESIII iron yoke started to be assembled, mapping magnet early 2005

• Preliminary date of the machine long shutdown for installation : Spring of 2005

• Tuning of Machine : Beginning of 2006

• BESIII detector moved to beam line, May 2006

• Machine-detector tuning, Machine-detector tuning, test run at end of 2006 test run at end of 2006

Schematic of BESIII detector

Major Upgrades in BESIII

• Superconducting magnet

• Calorimeter: BGO with E/E ~ 2.5 % @ 1GeV

• MDC IV: with small cell, Al wires and He gas

• Vertex detector: Scintillation fibers for trigger

• Time-of-flight : T ~ 65 ps

• Muon detector

• New trigger and DAQ system

• New readout electronics

Scintillating fiber for Trigger

1.27 mm or thinner Be beam pipe may be used

• R ~ 3.5 cm• 2 double-layers: one axis layer and one stereo layer• Scintillating fiber: 0.3*0.3 mm2, L~60 cm• Clear fibers: 0.3*0.3 mm2, L~1.4 m• two side readout by APD (Φ3) (below –300)• Signal/noise: <6 p.e.> / <~1p.e.>•

~ 50 m z ~ 1mm• Total # of channels: 27 x 8 = 216

Main Draft Chamber

• End-plates with stepped shape to provide space for SC quards and reduce background

– Inner part: stepped conical shape, cos θ= 0.93– Outer part: L = 190 cm, cosθ= 0.83 with full tracking volume

• cell size: ~ 1.4 cm x 1.4 cm• Number of layers (cell in R): 36

• Gas: He:C2H6 , or He:C3H8

• Sense wire: 30 m gold-plated W , • Field wire: 110 m gold-plated Al• Single wire resolution : 130 m• Mom. resolution : 0.8 % @ 1GeV &1T, 0.67% @1GeV&1.2T• DE/dx resolution: 7%

Trackerr simulation of MDC,

pt as a function of pt in % for pion, wire resolution 130 m

Trackerr simulation of MDC,

pt as a function of pt in % for pion, wire resolution 100 m

PID: Time of Flight Counters

• Double layers TOF: ( or TOF +CCT) plastic scintillator (BC-404) • 80 pieces per layer in • R: 66 ~ 75 cm, • Thickness 4 cm, length ~ 190 cm • Readout both sides by F-PMT • Time Resolution ~ 65 ps 2σon k/ separation: 1.1~1.5GeV/c (for polar angle 00~ 450) • For CCT option, need R&D

TOF+TOF TOF+CCT

BGO Barrel Calorimeter

To provide minimum space for main draft chamber and TOF and to obtain the necessary solid angle, one must modify L3 BGO crystals, and add new crystals

• 13 X0: E/E ~ 2.5 % @ 1GeV

• Rin ~ 75cm , Lin ~ 200cm cos = 0.83

• Cut L3 BGO crystals (10752) 22 X0 (24cm) into 13X0 (14cm) + 8.5 X0(9.5cm) • Making new bars of 14 cm by gluing 9.5cm + new crystal of 4.5cm • new BGO crystals needed.  

Electromagnetic Calorimetr with BGO(electron)

0. 0

2. 0

4. 0

6. 0

8. 0

10. 0

12. 0

0 0. 5 1 1. 5 2

Energy (GeV)

Res

olut

ion

(%)

L=13X0

L=15X0

Electromagnetic Calorimetr with BGO(photon)

0. 0

2. 0

4. 0

6. 0

8. 0

10. 0

12. 0

14. 0

0 0. 5 1 1. 5 2

Energy (GeV)

Res

olut

ion

(%)

L=13X0

L=15X0

Endcap Detector

Two possible technologies can be used,

1. CsI crystals as in the detector figure, similar technology as in the barrel, need endcap TOF.

2. Similar technique as KLOE using lead-fiber

technique, may not need TOF counters.

The first choice is preferred.

Superconducting Magnet for BESIII

• B: 1 ~ 1.2 T, • L ~ 3.2 m• Rin~ 105 cm, Rout ~ 145 cm Technically quite demanding for IHEP,no experience before, need collaboration from abroad and other institutes in China, both for coil and cryogenic system.

Muon Counter

• Barrel (L ~ 3.6m ) + Endcap: cos ~ 0.9

• Consist of ~ 12 layers stream tube or RPC

• Rin ~ 145cm (yoke thickness ~40cm)

• Iron plate thickness: 2-6 cm counter thickness: ~1.5 cm

• Readout hits on strips ~3cm

• total weight of iron: ~400 tons

0

10

20

30

40

50

60

70

80

90

100

0. 3 0. 5 0. 7 0. 9 1. 1 1. 3

Muon acceptance

Pion contamination

Interaction Region

It is very compact at IR, very close cooperation is needed in the designs of detector and machine components at IR

• Understand the space sharing, the support, vacuum tight

• Understand the backgrounds from machine and how to reduce them,

- Beam loss calculation (masks)

- Synchrotron radiation (masks)

- Heating effect (cooling if necessary)

• Understand the effects of the fringe field from SCQ to the detector performances

Luminosity Monitor

Because the situation at the IR, the luminosity has to either

be located quite far away from the IR (3-5m), or in front of

Machine Q magnet, to be designed carefully.

• Accurate position determination;

• Multiple detection elements at each side to reduce the

variation of luminosity when the beam position shifted

BGO crystals ?

Trigger

Trigger rate estimation (using the same trigger conditions as now)

• Background rate, with 40 times beam current and half of the beam lifetime, the rough estimation for the background is 80 times the current rate (10-15), or 800-1200 Hz, taking 1500 as a design number

• Good event rate When leave room for maximum luminosity to be as calculated, 11033, 200 times as current event rate, to be 1500 Hz

• Cosmic ray background can almost be negligible

Total peak trigger rate can be more than 3000 Hz, additional trigger (software) is needed to reduce the event rate to 2000Hz.

Level 0 and 1 are hardware triggers, latency 2.4s,

Level2 is software filtering using online computing farm

Because fastest detector element TOF need a time window of about 30 ns, the trigger can identify bunch train only, not individual bunch

• Level 0 with TOF signals

• Level 1 with hardware track finding, EMC clustering, total EMC energy, VC tracking or hits, counter hits

Front-end Electronics

Pipeline scheme is required

Requirements

• For the timing measurement

25 ps for TOF, 0.5 ns for MDC

• For charge measurement

1% accuracy for EMC, 2% for MDC and TOF

Total number of electronic channels ~ 76800 (too many muon channels?)

Data Acquisition System

Event builder 3000 Hz 6 K bytes ~ 20 Mb/s

Event filtering

Data storage

Run control

Online event monitor

Slow control

Switch network

Offline Computing and Analyses Software

• Computing, network, data storage, data base, processing management

• Supporting software package, data offline calibration, event reconstruction, event generators, detector simulation

Substantial manpower needed for software

Total CPU 36000 MIPS

Data storage 500 Tbytes/y on tapes, 24 Tbytes/y on disks

Bandwidth for data transfer 100 Mbps

• Vertex chamber ZHANG Qinjian

• Main drift chamber CHEN Yuanbo

• Time of flight counter HENG Yuekun

•EMC shower counter LU Jungguang

• Luminosity monitor WU Jian (USTC)

• Trigger system LIU Zhenan

• Front-end electronics SHENG Huiyi, ZHAO, Jingwei

• Data Acquisition HE Kanglin

• Computing and software MAO Zepu

Major New Subsystems of BESIII

Detector R&D

• A lot of new detector technology

• R&D for most sub-systems started

• Detector optimization is needed

• Modify the detector design when international collaboration is formed, new ideas are mostly welcome

Cost Estimation

• Detector: ~ 220M Chinese Yuan ( ~ 30 M US$ ) – 2/3 to 3/4 are from Chinese Government– International collaboration and contribution

are needed

Intl. Cooperation on BEPC II / BES III

• Intl. cooperation played key role in design, construction and running of BEPC/BES.

• Intl. cooperation will play key role again in BEPC II / BES III: design, review, key technology, installation, tuning ……

• Participation of foreign groups is mostly welcomed.

BESIII should be an international collaboration,

Establish organization accordingly.

If not enough fund is expected, 2nd option

Summary

• BEPC energy region is rich of physics, a lot of important physics results are expected to be produced from BESIII at BEPCII

• Detector design is started, need a lot of detailed work to finish detector design

• Very interesting and very challenging project

Thanks