[Tpe] TPE shielding
David Kashy
kashy at jlab.org
Thu Jan 27 17:40:25 EST 2011
Hello Larry,
I have verified that we can stack a concrete wall up to 5 ft high and 10
ft long on the decking next to the pair spectrometer magnet if
necessary. I used a block density of 150 lb/cubic ft. I think this is
what we have.
Thanks
Dave
On 1/27/2011 8:44 AM, Larry Weinstein wrote:
> Yes, that is correct.
>
> David Kashy wrote:
>> Larry,
>> If I understand correctly you want to add shielding on to the
>> platform that supports the pairspectrometer magnet..
>> Is this correct?
>>
>> Dave
>>
>>
>> On 1/26/2011 5:26 PM, Larry Weinstein wrote:
>>> Dear Dave,
>>>
>>> The wall is 10' wide. That is the approximate distance from the
>>> short ladder at the pair spectrometer to the upstream end of that
>>> platform. The wall height would then be beam height plus one foot.
>>> (I did not measure the height so I am not sure whether it would be
>>> 4' or 5'.)
>>>
>>> I completely agree that we should not rush into this. I think that
>>> the radiation experience since Thursday indicates that we do not
>>> need to do this immediately.
>>>
>>> - Larry
>>>
>>> David Kashy wrote:
>>>> Hi Larry,
>>>> Is this wall 10' high or wide?
>>>> If it is 10 ft wide then I guess we need to start it above the
>>>> floor level and need to design a beam structure to support it.
>>>>
>>>> If it is 10 ft tall we will still need to design a structure to
>>>> keep it from toppling.
>>>>
>>>> This wall will weight about 8000 lbs (similar to HYCAL) not a
>>>> trivial load and thus we must do it correctly.
>>>>
>>>> Thanks
>>>> Dave
>>>>
>>>>
>>>>
>>>> On 1/26/2011 4:55 PM, Larry Weinstein wrote:
>>>>> Dear Folks,
>>>>>
>>>>> Recommendation: In order to be very conservative, build a concrete
>>>>> wall on the beam left side of the collimator box, frascati magnet
>>>>> 1, and PS magnet. The wall would be about 10' x 5' x 1' and
>>>>> require 200 blocks. It should be built during the next extended
>>>>> down time (Tuesday?) so as not to interfere with taking data.
>>>>>
>>>>> Details: I spoke to Pavel Degtiarenko, the radiation and
>>>>> shielding expert. He says that there is very little useful data
>>>>> about the effect of radiation on electronics because the response
>>>>> of electronics to radiation is highly variable. He also noted
>>>>> that the existing BPM amplifiers have probably already suffered
>>>>> some radiation damage and that this damage is cumulative. He also
>>>>> said that most of the radiation is probably high energy particles
>>>>> that can be shielded by a shield wall (if we know the approximate
>>>>> source location.)
>>>>>
>>>>> This means that we probably want to add shielding to reduce the
>>>>> probability of catastrophic BPM failure.
>>>>>
>>>>> RadCon gave us the badge readings today (thanks, Becky!).
>>>>>
>>>>> 66016 331 1' from top of Acc IOC rack
>>>>> 66017 197 2.5' from top of Acc IOC rack, in front of concrete wall
>>>>> 66018 220 2.5' from bottom of Acc IOC rack, in front of concrete
>>>>> wall
>>>>> 66019 66 2.5 from top of Acc IOC rack, behind concrete wall
>>>>> 66020 73 2' from bottom of Acc IOC rack, behind concrete wall
>>>>> 66023 92 on ioc ptarg
>>>>>
>>>>>
>>>>> 66024 254 in front of new lead wall, 5' from floor
>>>>> 66025 191 L1-15 on left (upstream) side of IOC
>>>>> 66026 632 on railing opposite PS
>>>>>
>>>>> 66027 230 upstream, beam side of lead wall on ioctorus
>>>>> 66028 126 downstream, outside of lead wall on ioc torus
>>>>>
>>>>> The first column is the badge number, the second is the radiation
>>>>> dose, and the third is the location.
>>>>>
>>>>> A few notes: Badge 66026 with a reading of 632 mr is located where
>>>>> the radcon photon probe was located before 1/20, on the railing of
>>>>> the space frame close to the pair spectrometer. The probe was
>>>>> reading about 50 mr/hr at that location.
>>>>>
>>>>> Badge 66019, behind the concrete wall, is located directly on top
>>>>> of the accelerator BPM amplifiers and right next to the radcon
>>>>> photon probe which is currently reading 5 mr/hr. This is
>>>>> consistent with badge 66026.
>>>>>
>>>>> badges 66016, 7, and 8 are located on the accelerator BPM
>>>>> amplifier rack. The highest one (66016) has the highest dose and
>>>>> has much less of the lead shielding on the lead wall between it
>>>>> and the beam line. The concrete wall (either 6" or 12") reduces
>>>>> the rate from about 200 mr to 70 mr (comparing badges 17 and 18
>>>>> with 19 and 20). (Note that the badges were placed before the BPE
>>>>> shielding was added.)
>>>>>
>>>>> The maximum thickness of the lead wall reduces the dose from 254
>>>>> (badge 66024) to 92 (badge 66023).
>>>>>
>>>>> The radiation level is not much less a little further down-beam on
>>>>> rack L1-15 (191 mr at badge 25).
>>>>>
>>>>> The dose decreases about a factor of two between the upstream beam
>>>>> side of the lead wall on ioctorus to the downstream outside of the
>>>>> lead wall.
>>>>>
>>>>> Summary: The dose at iocptarg, ioctorus and the accelerator BPM
>>>>> amplifiers are within a factor of two. The shielding reduces the
>>>>> dose significantly.
>>>>>
>>>>> There is floor space or floor weight capacity to place any more
>>>>> shielding near the racks. THis means that the only place to add
>>>>> shielding is near the source. Since the source probably includes
>>>>> the collimator box, convertor and chicane, we should build a
>>>>> concrete wall on the beam left side from the PS magnet going as
>>>>> far upstream as possible.
>>>>>
>>>>> --
>>>>> Sincerely,
>>>>> Larry
>>>>>
>>>>> -----------------------------------------------------------
>>>>> Lawrence Weinstein
>>>>> University Professor
>>>>> Physics Department
>>>>> Old Dominion University
>>>>> Norfolk, VA 23529
>>>>> 757 683 5803
>>>>> 757 683 3038 (fax)
>>>>> weinstein at odu.edu <mailto:weinstein at odu.edu>
>>>>> http://www.lions.odu.edu/~lweinste/ <http://www.lions.odu.edu/%7Elweinste/>
>>>>
>>>> ------------------------------------------------------------------------
>>>>
>>>> Spam
>>>> <https://www.spamtrap.odu.edu/b.php?i=438400204&m=903a77671a30&t=20110126&c=s>
>>>> Not spam
>>>> <https://www.spamtrap.odu.edu/b.php?i=438400204&m=903a77671a30&t=20110126&c=n>
>>>> Forget previous vote
>>>> <https://www.spamtrap.odu.edu/b.php?i=438400204&m=903a77671a30&t=20110126&c=f>
>>>
>>> --
>>> Sincerely,
>>> Larry
>>>
>>> -----------------------------------------------------------
>>> Lawrence Weinstein
>>> University Professor
>>> Physics Department
>>> Old Dominion University
>>> Norfolk, VA 23529
>>> 757 683 5803
>>> 757 683 3038 (fax)
>>> weinstein at odu.edu <mailto:weinstein at odu.edu>
>>> http://www.lions.odu.edu/~lweinste/ <http://www.lions.odu.edu/%7Elweinste/>
>>
>>
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>
> --
> Sincerely,
> Larry
>
> -----------------------------------------------------------
> Lawrence Weinstein
> University Professor
> Physics Department
> Old Dominion University
> Norfolk, VA 23529
> 757 683 5803
> 757 683 3038 (fax)
> weinstein at odu.edu
> http://www.lions.odu.edu/~lweinste/
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