The MiniBooNE Target

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

2The BooNE Collaboration
Y. Liu, I. Stancu
University of Alabama, Tuscaloosa, AL 35487
S. Koutsoliotas
Bucknell University, Lewisburg, PA 17837
E. Hawker, R. A. Johnson, J. L. Raaf
University of Cincinnati, Cincinnati, OH 45221
T. Hart, R. H. Nelson, E. D. Zimmerman
University of Colorado, Boulder, CO 80309
A. A. Aguilar-Arevalo, L. Bugel, J. M. Conrad,
J. Formaggio, J. Link, J. Monroe, D. Schmitz,
M. H. Shaevitz, M. Sorel, G. P. Zeller
Columbia University, Nevis Labs, Irvington, NY 10533
D. Smith
Embry Riddle Aeronautical University, Prescott, AZ 86301
L. Bartoszek, C. Bhat, S. J. Brice, B. C. Brown, D. A. Finley,
B. T. Fleming, R. Ford, F. G. Garcia, P. Kasper, T. Kobilarcik,
I. Kourbanis, A. Malensek, W. Marsh, P. Martin, F. Mills,
C. Moore, P. Nienaber, E. Prebys, A. D. Russell,
P. Spentzouris, R. Stefanski, T. WilliamsFermi National Accelerator Laboratory, Batavia, IL 60510

D. Cox, A. Green, H. Meyer, R. Tayloe
Indiana University, Bloomington, IN 47405
G. T. Garvey, C. Green, W. C. Louis, G. A. McGregor,S. McKenney, G. B. Mills, V. Sandberg, B. Sapp,
R. Schirato, N. Walbridge, R. Van de Water, D. H. White
Los Alamos National Laboratory, Los Alamos, NM 87545
R. Imlay, W. Metcalf, M. Sung, M. O. Wascko
Louisiana State University, Baton Rouge, LA 70803
J. Cao, Y. Liu, B. P. Roe
University of Michigan, Ann Arbor, MI 48109
A. O. Bazarko, P. D. Meyers, R. B. Patterson,F. C. Shoemaker, H. A. Tanaka
Princeton University, Princeton, NJ 08544

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

3MiniBooNE Overview
LMC

8GeVBooster+Kπ+magnetic hornand target?
νµ→νeµ+νµdecay pipe
25 or 50 mab

so 450 m dirt
rb er

detector

The FNAL Booster delivers 8 GeV protons to the MiniBooNE beamline.
The protons hit a beryllium target producing pions and kaons.
The magnetic horn focuses the secondary particles towards the detector.
The mesons decay, and the neutrinos fly to the detector.

¾Signal from π+→µ+ νµ …then… νµ →νe …which produces… e- in the detector.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

4Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

5Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

6Target Information• Initially the target was integral to the horn (Al).
• The target was separated from the horn to allow suitable handling,
replacement and disposal of the horn.
• Specifically, this reduces the activity level of the horn.
• The building crane was unable to lift the combined assembly (+ requiredshielding).
• Allows target to be replaced without replacing horn.
• Necessitates separate cooling system for target.

• Be chosen for the target material.
••
•
•
•

Minimizes remnant radioactivity.
Excellent thermal and mechanical properties.
High pion yield.
Low energy deposition per unit length (minimizes load on cooling system).
Be highly toxic, requiring special handling procedures.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

7Target Information• Original design was a closed target, fabrication difficulties
cause design to be revised to an open target.
• Fully instrumented air cooling system.
• Target electrically coupled to the horn.
• 7 slugs, each ~10cm long (0.25 interaction lengths) and1cm in diameter.
• Building target from slugs minimizes any forces on theassembly due to off axis asymmetrical heat loads from theprimary proton beam.
• One of the cooling pipes given over to house cables fromthe target multiwire.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

8Target Information• 1.6μs spill of 5×1012 protons, at an average rate of 5Hz.
• Energy deposited in the target is 120J per pulse, or 600W.
• Thermal shock of pulse causes a pressure wave of~20MPa (Be has a fatigue limit of 300MPa).
• 7Be (T½ = 53 days) produced in the target. Target will
become ~100Rhr-1 on contact.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

9Original Closed DesignOuter TubeAir Flow

TargetInnerTube

Cooling Fins

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

10Present Open DesignOuter Tube

Air Flow

TargetCooling Fins

The open configuration has 42% more surface area and1.98 times the mass of air flow of the closed design.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

11Target Cooling System•Beam permit is interlocked withboth the target and return airflow
switches. These switches would
immediately sense any majorleak between themselves andthe blowers.
•Thermal sensors would pick up
any major leak in the line
upstream of the flow switch.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

12Target Schematic

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

13

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

14

Images courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

15

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

16

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

17

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

18

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

19

Return air temperature
sensors are located here.
Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

20

Image courtesy of
Bartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

21

Image courtesy ofBartoszek Engineering.
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

22

Web Target Monitoring

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

23Target Temperature

The target temperature isvery sensitive to whether
the beam is on target.
It’s not the only measure,but can be used as a
powerful cross check of theBPMs and multiwires.

Structure dueto timeline.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

24

Be in the Air Scare• August 28th wipe showed a 5 fold increase in the amountof 7Be on the floor near the target cooling manifold(~65nCi compared with ~13nCi previously).
• High readings were found only in this location, not inother locations tested in MI12.
• During the current shutdown, the target cooling system
was inspected and checked for leaks.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

25

Be in the Air Scare• Fittings around 3 of the monitoring devices were found to becompromised, likely due to radiation damage to organics used in theseals (Teflon). These leaks were all downstream of the HEPA filter.
These leaks could have been the cause of the high readings. They
have now been fixed.
• The HEPA filter was inspected and replaced. Old filter showed novisible signs of radiation damage.
• “Grit” was found in the upstream pipe into the HEPA filter. Chemical
analysis showed no Be, but Al2O3 and Cu were present. The originof the grit is unknown, but suspected to be the horn box.

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

26

NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor

27

Conclusions• The target and cooling system seem to be performing well.
• No conclusive explanation of the high Be readings in August
has been found. They are consistent with air activation in thetarget region.
• There is no evidence to suggest that the target is degradingin any way, or that the target was the source of the high Bereadings.
• With beam intensity at ~35% of the goal, the target has yet tobe stressed. Hopefully summer shutdown work at FNAL
(almost complete) will change this!
NBI03, Tsukuba, Japan.
Saturday, November 8th, 2003

Gordon McGregor