[Tpe] TPE shielding

Thu Jan 27 08:37:46 EST 2011

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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