Daya Bay, Physically - Virginia Tech

Daya Bay, Physically

VTcentric

Complied by Jo Ellen Narron

Location

U.S.:

BNL, Caltech, Cincinnati, George Mason, Houston, IIT, Iowa State, LBNL, Princeton, RPI, UC Berkeley UCLA, UIUC, Virginia Tech, Wisconsin

Asia:

Beijing Normal, Chengdu U. of Tech., CGNPE, CIAE, CUHK, Dongguan Polytech, IHEP Beijing, Nankai, Nanjing, National Chiao-Tung U., National Taiwan U., National United U., Shangdong U., SJTU, Shenzhen U., Tsinghua U., HKU, USTC, Zhongshan U.

Europe.:

Charles U., JINR, Kurchatov Institute

The Daya Bay Collaboration

Jon Link Dayabay at LowNu 2009

Daya Baycores

Ling Aocores

Ling Ao IIcores

Daya Bay NearOverburden: 98 m

Ling Ao NearOverburden: 112 m

Far siteOverburden: 355 m

Daya Bay: Experimental setup • 8 identical anti-neutrino detectors ( two at each near site and four at the far site) to cross-check detector efficiency• Two near sites sample flux from reactor groups

Daya Bay Near (m)

Ling AoNear (m)

Far (m)

Daya Bay 363 1347 1985

Ling Ao I 857 481 1618

Ling Ao II 1307 526 1613

(Starting 2011)

9 different baselines under the assumption

of point size reactor cores and detectors

CoresHalls

Deb Mohapatra Meeting of APS Division of Particles & Fields

Ehs & Water Pools

Far Hall

Jinyu Fu & Lingshu Wang DocDB2333v3

Near Daya Bay Hall

Near Ling Ao Site

A Near Hall

Kwong Lau DocDB2049v2

13

Pool Cover System

General Description

Pool surface covered by Ø10cm float balls which support a .045” (1.1mm) thick Hyperlon light-tight cover

Side Elevation

NTS

Small Pool

• Area = ~1530 sq. ft.

• Perimeter = ~150 ft.

Large Pool

• Area = ~2571 sq. ft.

• Perimeter = ~188 ft. Charlie Pearson DocDB4340v3

Muon veto system

CerenkovWater Pool (2 Zone)

RPC’s

PMTs(962)

• Two tagging systems to detect cosmic ray and fast neutron background: 2.5 meter thick two-section water shield and RPCs

• Efficiency 99.5% with uncertainty <0.25%


Water Shield and Muon Tagging System

Water Pool

RPCs

The water pool shields the detectors from energetic γ-rays from the decay chains of 238U, 232Th and 40K in surrounding the rock

It also detects the Čerenkov light produced by cosmic ray muons which pass near the detectors

The pool is lined with white Tyvek and sparsely populated with PMTs

The pool is optically separated into two zones (inner and outer)

The two zones allow a better measurement of efficiency

The top is covered with 4 layers of RPC Minimum 2.5 m water shielding in

all directions.

Construction of the water pool at the Daya Bay Near site

Jon Link Dayabay at LowNu 2009

Far Hall PMT Support Assembly

Near Hall PMT Support Assembly



Muon Calibrationaka: muCal

One of VT’s Major efforts, we are responsible for the calibration of the

PMTs in the water pool.

RPCs & Support

VTs other major effort is the development of the RPC HV system

35

Electrical Structure of the RPC Modules

Key design elements:

1. Aluminum box is electrically isolated from the signal lines, which are isolated from the HV

2. Positive and negative HV are well separated by arraigning the voltages on the electrodes as: +--++--+

3. Pick-up planes are separated from other RPCs to avoid cross tralk.

Interface on the Top panel

All connectors are installed on the top panel

two HV Slots: 95mm x 22mmFour screw holes near the slot to hold the HV interface box in place

HV slotHV slot

FEC slot

Gas vent hole Gas vent hole

4 flat Signal cables are connected to FEC which screwed on the top panel

HV

FECHV

Slot:150mm x 40mm(inside) 4- Ø10mm holes (outside )

4 inlet and 4 outlet pass through the gas vent as shown in the picture.

Xiaoyan Ma DocDB2332v5

37

RPC Interface Box

RPC Module

Each Interface box takes four input voltages (one for each plane) and splits each line to the two 1m × 2m RPC chambers.

Kwong Lau DocDB2049v2

Flexible cable tray to avoid disconnecting the cables

• The configuration of the flexible cable tray is shown in the above plot,

• One end of the flexible cable tray is fixed at the trench , the other end is fixed at the center of RPC support structure, (details in next slides)

• Given R=0.2m, offset=1m, we need 12.3m flexible cable tray for each site,

• The RPC’s will move as a single unit except for repairing.

Far site pool

Total Length = 9.65m + π*R+ 2*offset

R is the bending radius,

Offset gives convenience to installation

Mengyun Guan & Changgen Yang DocDB2370v5

Pool Cover 42

RPC Support Structure

Black Polypropylene float ball

Veto PMTs Unistrut Support Frame

Cable Trench

Side Elevation in Section

Charlie Pearson DocDB4340v3

RPC Structure PRR and Module FDR

Introduction

Changgen Yang

24 June 2008

RPC module number: 9×9(far site) , 9×6(near site)Each module has the same size (2190mm×2150mm×82mm)Module overlap on the support frameModule weight: 200Kg /module

Module layout

Rail direction


Sub-support for higher layer

sub-support for higher layer have the similar structure as the lower layer

But two pieces of U-steel add to block up the L-steel to the suitable position to limit the moving of the module.

A

View A


The detail of the distribution panels

• The 19’ standard racks will be ordered for custom-made in China.

• The above plot shows the distribution panels with the most channels, the size is of real scale.

• The height of the racks is convenient for reading and adjusting.

• HV/signal units and gas units should be sit in different racks.

• The platform for standing the racks is supported by three legs extending from the edge of the RPC support structure.

Blue represents HV fan out,

Red represents signal ROT,

Green shows gas distribution boxes.

Mengyun Guan & Changgen YangDocDB2370v5

Cable/tube routing detail

3. The cables/tubes from the distribution boxes to RPC modules go through under the edge part of the main support structure and then up to the Racks .

The right plot shows the side view of the position of trench, cable drag chain, the fixed cable tray and the support structure together,

The drag chain will be put in the bottom of the trench along the rail when the RPC support structure is above the water pool (in most time),

The drag chain should possess the whole right part of the trench, we plan to apply “U” shaped tray to hold the drag chain and keep other cables out of the space above it,

When we need to push the RPC support structure to the far end of the hall, the cover board on the trench need to be uncovered in advance.

3


The overall scheme of the distribution panels

• The RPC gas monitor chamber & driving control crate is putting together with the gas/HV/sig distribution devices,

• The HV fan out panel and the gas distribution panel are of the latest picture, while the ROT is still unknown.


Cable/tube routing detail

1. The main gas supply pipe (2), power supply line (2/?), signal fiber (4/6 for near/far), and HV cable (48/72 for near/far) go through the drag chain to the center of the support structure.

2. Then the main fold cables/tubes go oppositely to the two side of the support structure along the fixing cable tray.

12

Trench

layout

Cable drag chain


52

A1733P(N)

12 channels

+(-) 4 kV

2 mA

No floating return

CAEN Hardware

SY1527LC

Same mainframe as used for the PMT HV

16 slots

Fan Out

The fan out will consist of a custom commercially produced rack mounted box with ten SHV bulkhead connectors (Kings 1704-1).

The box will look something like this, only not so deep, and will come with 10 SHV “D” holes punched on the front face.

54

High Voltage Multiplexing

Each HV channel will power 9 RPCs planes and will be split by a multiplexing box that will move with the RPCs.

The cables from the mainframe will reside in a folding cable tray and will have enough slack to accommodate the movement.

The multiplexing box will split 1 coaxial cable from the mainframe to 9 single conductor cables to separate RPCs.

The RPC interface box will attach to the edge of the RPC module with four screws.

HV and ground connecting cables will pass through a slot in the Interface box matted to a slot in the RPC module box.

RPC Interface

Cable Length CalculationMainframe to Fanout

Variable Lengths

• Distance from Folding Cable Tray to Fanout

• 1m added for each RPC support structure break crossed

• 10% wiggle added

Column:

1 2 3 4 5 6 7 8 9

ADsAD = anti-neutrino detector

At VT we work in the muon tagging system. This allows us to know when

a muon goes by our AD (which we care deeply about) Here is the brief

and dirty version of the Ads . . . .

AD calibration system

automated calibration system

Automated calibration system→ routine weekly deployment of sources

LED light sources → monitoring optical properties

e+ and n radioactive sources (=fixed energy)→ energy calibration

• 68Ge source• Am-13C + 60Co source• LED diffuser ball

Deb Mohapatra Meeting of APS Divisionof Particles & Fields

Fabrication and delivery of detector components

acrylic target vessels

detector tank


Target mass measurementfilling platform with clean room

ISO Gd-LS weighing tank

pump stations

detector

load cell accuracy < 0.02%

Coriolis mass flowmeters < 0.1%

200-ton Gd-LS reservoir

20-ton ISO tank

filling “pairs” of detectorsDeb Mohapatra Meeting of APS Divisionof Particles & Fields

The End

• Do you understand it all now?

• I doubt it, it took me a while and I still don’t call myself an expert.

• Questions?!!??!!?

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Daya Bay, Physically - Virginia Tech